Wireless communication system and method and system for detection of position of radio mobile station

ABSTRACT

A method of detecting a position of a radio mobile station in radiocommunications, which is capable of accurately and simply finding the position of the mobile station. At a measuring point the mobile station measures the reception radio strength levels from a plurality of base stations and conveys the measurement results through the base station to a control station. The control station learns, through a neural network, the correlation between the reception radio strength levels and the position of the mobile station on the basis of the measurement results at a plurality of measuring points and the positions of the measuring points. Subsequently, when the mobile station communicates to the control station the reception radio strength levels measured at an arbitrary point, the control station estimates the position of the mobile station, causing those measurement results, on the basis of the correlation obtained through the learning.

This application is a Division of application Ser. No. 08/819.985 filedMar. 18, 1997 U.S. Pat. No. 6,140,964.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mobile station position detectionmethod and a system for detecting a position of a person or object whoor which carries a mobile station in wireless radiocommunications and aradiocommunication system based thereupon, which are capable ofaccomplishing the detection of the position of the mobile station with ahigh accuracy.

2. Description of the Prior Art

In wireless communication fields such as portable radio telephonesystems and personal handy-phone systems (PHS), a radio wave strength(an electric field strength) level at reception varies in accordancewith the distance from a base station. This signifies that the detectionof the strength levels of radio waves picked up from a plurality of basestations in a mobile station side allows the detection of the positionof the mobile station, i.e., the position of a person or object who orwhich carries the mobile station. However, in the case of radiocommunication systems such as prior portable telephones and PHSs where aplurality of radio zones constitute a service area, the specification ofthe present location of a mobile station is limited to within arelatively wide area being the range of a radio zone of a base stationwhich accepted the position registration of the mobile station (therange of a general calling area composed of a plurality of radio zonesincluding the radio zone of the base station which accepted the positionregistration).

For the accurate detection of the location of the mobile station, forexample, in the “Mobile Station Position Detection Method” disclosed inJapanese Unexamined Patent Publication No. 2-44929, applying the factthat the radio zones of a plurality of base stations overlap with eachother, the present location of the mobile station is specified to asmaller area than the radio zone of one base station on the basis of themobile station reception radio strength levels from the plurality ofbase stations and the electric field strength map in the radio zone ofeach of the base stations. The outline of the typical arrangement of theposition detection method disclosed in Japanese Unexamined PatentPublication No. 2-44929 will be described hereinbelow with reference toFIG. 20.

A radiocommunication system, introducing this prior mobile stationposition detection method, as shown in FIG. 20, comprises base stations2802, 2803, 2804 respectively having radio zones 2805, 2806, 2807, amobile station 2801 existing in these radio zones, a mobilecommunication control station 2808 for taking charge of control ofcommunications between the base stations or between the base stationsand a wire network, and a position information center 2809 for detectingthe position of the mobile station 2801 on the basis of the informationattainable through the mobile communication control station 2808. Thepositional information center 2809 is composed of a positionalinformation transmission and reception unit 2810 for collectinginformation about reception radio strengths of the respective basestations 2802, 2803, 2804 and an electric field strength map 2811indicative of the electric field strength distribution of the respectiveradio zones 2805, 2806, 2807.

The mobile station 2801 stands in a spot at which the radio zones 2805,2806, 2807 of the plurality of base stations 2802, 2803, 2804 overlapwith each other and, hence, can receive radio waves transmitted from thebase stations 2802, 2803, 2804. If the mobile station 2801 is not in aconnected communication state with a specific base station, the mobilestation 2801 is capable of receiving radio signals (for example,information including identifiers of the base stations, intermittentlytransmitted through control channels) from these base stations 2802,2803, 2804.

When receiving the radio signals transmitted from the base stations2802, 2803, 2804, the mobile station 2801 measures the strength levelsof these radio signals and transmits the reception radio strengths onthe respective base stations 2802, 2803, 2804, together with the basestation identifiers, through any one of the base stations 2802, 2803,2804 to the mobile communication control station 2808. The mobilecommunication control station 2808 communicates the reception radiostrengths on the base stations 2802, 2803, 2804 from the mobile station2801, toward the positional information transmission and reception unit2810 of the positional information center 2809. The positionalinformation center 2810 stores the electric field strength map 2811 madein advance and representative of the electric field strengthdistribution in the radio zones of all the base stations which, themobile communication control station 2808 manages, in the form of fieldstrength contours. In the positional information transmission andreception unit 2810, on the basis of the electric field strength map2811 on the base stations 2802, 2803, 2804, the field strength contourscorresponding to the reception radio strength levels on the basestations 2802, 2803, 2804 from the mobile station 2810 are drawn toattain an area in which the respective field strength contours intersectwith each other. This area is a spot detected as the position at whichthe mobile station exists. Thus, the position detection method disclosedin Japanese Unexamined Patent Publication No. 2-44929 can specify theposition of the mobile station to within a smaller range than the radiozone of one base station, thereby realizing a position detection with ahigh accuracy.

However, for applying the position detection method disclose in JapaneseUnexamined Patent Publication No. 2-44929, it is necessary that theelectric field strength map on the base stations constituting a servicearea is known in advance. In general, the electric field strengthdistribution on some base station is affected by various obstacles orreflectors (roads, houses, buildings and others in the outdoor places,and floors, ceilings, partitions and other in the indoor places) whichexist within its radio zone, great difficulty is encountered to predictthis electric field strength map from the radio wave characteristic ofthe base station, and therefore, detailed measurements using a fieldstrength meter or the like are required in order to find the electricfield strength map at every base station. In fact, for example, in FIG.4 (p. 773 (61)) of “Arrangement of PHS Terminals” written by Nakamura,Akazawa, Oka and Mizutori in the Document “NTT R&D” No. 9 (Vol. 44)1995, pp. 769 (57)-pp. 774(62), there has been shown an electric fieldstrength distribution on a PHS base station in a house. Referring tothis, the PHS electric field strength distribution obviously assumes anextremely complicated configuration in a room.

For this reason, for improving the position detection accuracy in thismethod, a more accurate electric field strength map is required to beobtained through measurements. However, the measurements of the electricfield strength distributions on all the base stations requireexceedingly expansive labor. Accordingly, the detection of the positionof the mobile station with a higher accuracy than that due to the radiozone of one base station is approximately impossible or extremelydifficult if taking into consideration the exceedingly expansive laborrequired for the production of the electric field strength map.

Moreover, for eliminating the above-mentioned problem, the report “Studyon Mobile Station Position Detection Based upon Reception LevelInformation” Electronic Information Communication Scientific SocietyAutumn Meeting B-269 (1993) presents a method to specify the presentlocation of a mobile station to within a range smaller than a radio zoneof one base station through the use of mapping table of reception radiostrength levels from a plurality of base stations received by the mobilestation and a position (X, Y) of the mobile station by using the factthat the radio zones of the plurality of base stations overlap with eachother. This position detection method will be described hereinbelow withreference to FIG. 21. For the basic data for the position detection,reception radio strength levels from a plurality of base stations aremeasured at points within a service area, and the positions (X, Y) ofthe measuring points and the radio strength levels (E1, E2, E3, E4 andE5) from base stations BS1, BS2, BS3, BS4 and BS5 received there aremade to correspond to each other and accumulated in a database in acenter processing section in advance. In the case of detecting theposition of the mobile station, radio strength levels (E1′, E2′, E3′,E4′ and E5′) received from the plurality of base stations aretransmitted to a center to be checked with the closest radio strengthlevels of the radio strength levels accumulated in the database of thecenter to estimate the position (X′, Y′) of the mobile station. Thus,the position detection method described in the report “Study on MobileStation Position Detection Based upon Reception Level Information” canestimate the position of the mobile station within a range smaller thanthe radio zone of one base station.

There is a problem which arises with this position detection method,however, in that since the estimation of the position is made in themanner that the closest reception radio strength data is retrieved inthe position database, the estimated position is limited to the actualmeasuring points. In addition, in general the recognition of a place ismade with a floor or room number in the case of an indoor place and witha building or inherent area name in the case of an outdoor place, andthe recognition using the coordinates is inconvenient in many cases.Accordingly, in the case of detecting the position expressed with such adiscrete value, it is considered that this position detection method ismade such that, for example, the correspondence between room numbers andcoordinates is prepared in advance and the estimated position of themobile station is converted into a room number. However, the theposition estimated in terms of a room greatly differs from the positionestimated with respect to the vicinity of the boundary between rooms,and hence, even if the closest point is specified on the reception radiostrength levels, the error rate increases so that difficulty isencountered to know the degree of the reliability of the positiondetection.

SUMMARY OF THE INVENTION

The present invention has been developed in order to eliminate theabove-mentioned problems, and it is therefore an object of the presentinvention to provide a radio mobile station position detection methodwhich is capable of accurately and simply finding the position of amobile station to promote the reliability of the position detection anda radiocommunication system based upon the aforesaid position detectionmethod of the mobile station.

In a position detection method of a mobile station according to thepresent invention, the mobile station measures the reception radio wave(electric field) strength levels from a plurality of base stations at ameasuring point to convey the measurement results through a base stationto a control station, while the control station uses a neural network tolearn a correlation between the reception radio strength levels and theposition of the mobile station on the basis of the measurement resultsat a plurality of measuring points and the positional data at themeasuring points. Further, when the mobile station sends the measurementresults of the reception radio strengths from the plurality of basestations measured at the plurality of measuring points, the controlstation estimates the position of the mobile station bearing themeasurement results on the correlation between the reception radiostrength levels and the positions of the mobile station obtained throughthe learning.

In addition, the control station communicates the structure of theneural network experiencing the learning to the mobile station, so thatthe mobile station measures the reception radio strength levels from theplurality of base stations to detect its own present position on thebasis of the measurement results. Further, the plurality of basestations measure the reception ratio strength level from the mobilestation at a measuring point and conveys the measurement results to thecontrol station which in turn, learns the correlation between thereception radio strength level at each of the base stations and theposition of the mobile station through the neural network on the basisof the measurement result in each of the respective base stations andthe positional data at the measuring point. When the respective basestations transmit the measurement results on the reception radiostrength levels of the radio wave emitted from the mobile station at agiven point, the control station estimates the position of the mobilestation on the basis of the correlation it learns.

Furthermore, in a wireless radiocommunication system according to thepresent invention, a mobile station is equipped with radio strengthmeasuring means for measuring the reception radio strength levels from aplurality. of base stations, whereas a control station is provided withposition input means for accepting or inputting the position of ameasuring point, position learning processing means for learning,through a neural network, the correlation between the reception radiostrength levels measured by the mobile station at a plurality ofmeasuring points and the position of the measuring point inputted fromthe position inputting means, and position estimation processing meansfor, using the reception radio strength levels from the plurality ofbase stations measured by the mobile station at a given point,estimating the position of the mobile station at the measuring time onthe basis of the correlation the position learning processing meanslearns.

In addition, the mobile station is equipped with learning result storagemeans for storing parameters of the neural network conveyed from thecontrol station and position calculation means for constructing a neuralnetwork through the use of the parameters to detect its own position.Further, each of the base stations is provided with radio strengthmeasuring means while the control station includes position input meansfor accepting the position of the measuring point, position learningprocessing means for learning, through a neural network, the correlationbetween the reception radio strength levels from the mobile stationmeasured by the respective base stations and the position of themeasuring point, and position estimating means for estimating theposition of the mobile station on the basis of the reception radiostrength levels from the mobile station measured by the respective basestations.

Thus, according to this invention, since the detection of the positionof the mobile station is accomplished through the learning by the neuralnetwork, the measuring work at the preparation stage is satisfied withthe measurements of the reception radio strength levels at a typicalmeasuring point, with the result that the working quantity can bereduced in the preparation stage.

In accordance with an aspect of the present invention, in a positiondetection method for detecting a mobile station in a wirelessradiocommunication system including the mobile station, base stationsand a control station, the mobile station measures the reception radiostrength levels from a plurality of base stations at a measuring pointand communicates the measurement results through the base station to thecontrol station which in turn, learns, through a neural network, thecorrelation between the reception radio strength levels and the positionof the mobile station on the basis of the measurement results at aplurality of measuring points and the positional data of the measuringpoints, and when the mobile station conveys the measurement results ofthe reception radio strength levels from the plurality of base stationsmeasured at a given point through the base station to the controlstation, the control station estimates the position of the mobilestation producing the measuring results on the basis of the correlationbetween the reception radio strength levels and the positions of themobile station attained through the learning. Accordingly, owing to thelearning of the correlation between the positions of the mobile stationand the reception radio strength levels from the plurality of basestations at that point, the estimation of the position of the mobilestation is possible on the basis of the electric field strength levelsof the plurality of base stations the mobile station receives at thegiven point.

Furthermore, another aspect of this invention is that the measuringpoints are determined in advance and each of the mobile stationsmeasures the reception radio strength levels from a plurality of basestations at its own measuring point so that the learning is made of thecorrelation between the reception radio strength levels measured at themeasuring point predetermined in position beforehand and the position ofthe measuring point. Still further, the measuring point is set to aplace at which a charger for charging the mobile station stands so thatthe reception radio strength levels are measured and reported to thecontrol station while the mobile station is located on the charger knownin position for the charging. The control station learns the aforesaidcorrelation on the basis of the positional data of the charger and thereported reception radio strength levels.

Moreover, a further aspect of this invention is that the mobile stationcommunicates the positional data of a measuring point and the receptionradio strength levels from a plurality of base stations measured at themeasuring point through the base station to a control station. Themobile station measures the reception radio strength levels from theplurality of base stations and inputs its own position through the inputby the user or through a position detection unit to report both themeasured reception radio strength levels and its own position to thecontrol station. The control station learns the aforesaid correlation onthe basis of the position of the mobile station and the reception radiostrength levels at that point.

In addition, a further aspect of this invention is that the mobilestation measures the reception radio strength levels from a plurality ofbase stations plural times at the same measuring point or an arbitrarypoint and statistically processes the plurality of measurement values tooutput the obtained single value as a final measurement result, whichcan enhance the accuracy of the measurement result in the mobilestation. Further, when the mobile station conveys the measurementresults of the reception radio strength levels from a plurality of basestations measured at an arbitrary point through the base station to thecontrol station, the control station estimates the position of themobile station corresponding to the measurement results on the basis ofthe correlation between the reception radio strength levels and thepositions of the mobile station obtained through the learning andcommunicates the estimation result to the mobile station. Accordingly,the user who carries the mobile station can find his own positionthrough the inquiry to the control station.

Furthermore, a further aspect of this invention is that, when a mobilestation inquires for the position of a different mobile station, acontrol station gives instructions to the different mobile station tomeasure the reception radio strength levels from a plurality of basestations and to report them, and in response to the report of themeasurement results, the control section estimates the position of thedifferent mobile station on the basis of the measurement results andconveys the estimation result to the mobile station which made theinquiry therefor. Accordingly, the user who carries the mobile stationcan find the position of a person carrying the different mobile stationby the inquiry to the control station.

Still further, a control station successively stores the estimationresults of the position of a mobile station, and when estimating theposition of the mobile station on the basis of a new measurement result,the control station decides, on the basis of the past positions of themobile station, whether or not the estimated position of the mobilestation is appropriate. If not appropriate, the control station givesinstructions to the mobile station to again make the measurements. Thus,the reliability of the estimation results can improve through thisprocedure. Besides, the mobile station measures the reception radiostrength levels from a plurality of base stations at a given equal timeinterval and conveys the measurement results through the base station tothe control station. The control station obtains the position of themobile station at the equal time interval on the basis of themeasurement results and stores them in time series, with the result thatit is possible to more accurately judge the appropriateness of theposition of the mobile station newly estimated.

In addition, a further aspect of this invention is that a controlstation converts the reception radio strength level transmitted from amobile station into a theoretical distance between the mobile stationand a base station and learns, through a neural network, the correlationbetween this theoretical distance and the position of the mobilestation, so that the learning processing becomes easy and theimprovement of the learning accuracy becomes possible.

Moreover, in a position detection method for detecting the position of amobile station in a wireless radiocommunication system equipped with themobile station, a plurality of base stations and a control stationaccording to this invention, the mobile station measures the receptionradio strength levels from the plurality of base stations at a measuringpoint and communicates the measurement results through the base stationto the control station, which in turn, learns, through a neural network,the correlation between the reception radio strength levels and thepositions of the mobile station on the basis of the measurement resultsat a plurality of measuring points and the positional data of themeasurement points and further conveys the parameters of the neuralnetwork obtained through the learning to the mobile station, while themobile station constructs a neural network through the use of theparameters and detects its own position on the basis of the receptionradio strength levels from the plurality of base stations measured at anarbitrary point through the use of the constructed neural network. Withthis method, the mobile station can detect its own position without theinquiry to the control station.

In addition, a control station learns, through a neural network, thecorrelation between the reception radio strength levels and areas suchas a room and a zone having an extension in which a mobile stationstands, with the result that the room or zone in which a person carryingthe mobile station exists is detectable and it is possible to present aplurality of places as the candidates for the person's whereabouts.

Furthermore, in a position detection method for detecting the positionof a mobile station in a wireless radiocommunication system equippedwith the mobile station, base stations and a control station, each ofthe base stations measures the reception strength level of a radio waveemitted from the mobile station standing at a measuring point andconveys the measurement result to the control station, while the controlstation learns, through a neural network, the correlation between thereception radio strength levels and the positions of the mobile stationon the basis of the measurement results at a plurality of measuringpoints and the positional data of the measuring points, and when each ofthe base stations measures the reception radio strength level of a radiowave emitted from the mobile station standing at an arbitrary point andconveys the measurement result to the control station, the controlstation estimates the position of the mobile station bearing themeasurement results on the basis of the correlation between thereception radio strength levels and the positions of the mobile stationobtained through the learning. Thus, it is easily applicable to a systemsuch as a mobile radio telephone system and PHS where a plurality ofbase stations measures the radio wave transmitted from a mobile station.

Moreover, in a wireless radiocommunication system equipped with a mobilestation, base stations and a control station and allowing the controlstation to detect the position of the mobile station, the mobile stationis equipped with radio strength measuring means for measuring receptionradio strength levels from a plurality of base stations, while thecontrol station is provided with position input means for receiving theposition of a measuring point, a position learning processing means forlearning, through a neural network, the correlation between thereception radio strength levels by the mobile station at a plurality ofmeasuring points and the positions of the measuring points inputtedthrough the position input means, and position estimation processingmeans for estimating, on the basis of the reception radio strengthlevels from the plurality of base stations measured by the mobilestation at an arbitrary position, the position of the mobile station atthe measuring time through the use of the correlation the positionlearning processing means learn. Thus, the detection method based uponthe learning by the neural network is practicable for the positiondetection of the mobile station.

Furthermore, a mobile station is equipped with radio strength measuringmeans for measuring the reception radio strength levels from a pluralityof base stations, whereas a control station is provided with positionstorage means for storing the position of each of measuring points andan identifier of the mobile station corresponding to the measuringpoint, position learning processing means for learning, through a neuralnetwork, the correlation between the reception radio strength levelmeasured at the measuring point by the mobile station and the positionof the measuring point stored in the position storage means, positionestimation processing means for estimating the position of the mobilestation at the measuring time on the basis of the reception radiostrength levels from the plurality of base stations measured by themobile station at an arbitrary point through the use of the correlationthe position learning processing means learns. This system can adopt aposition detection method in which the learning is conducted using thereception radio strength level measured by a predetermined mobilestation at a predetermined measuring point.

In addition, for charging a mobile station is located at a measuringpoint, so that the mobile station reports the reception radio strengthlevel measured during the charging to a control station whereas thecontrol station learns using the reception radio strength level and theposition of the charger known in advance. Further, at the position ofthe measuring point, there are situated a learning data collectorprovided with radio strength measuring means for measuring receptionradio strength levels from a plurality of base stations and transmissionand reception means for transmitting the measured radio strength levelsthrough the base station to a control station and further for receivinga control signal from the control station, with the result that thecontrol station can learn using the reception radio strength levels sentfrom the learning data collector at regular intervals or in accordancewith commands.

Furthermore, a mobile station is equipped with radio strength measuringmeans for measuring the reception radio strength levels from a pluralityof base stations and position input means for taking in its own positioninformation, whereas a control station is provided with positionlearning processing means for learning, through a neural network, thecorrelation between the reception radio strength levels measured by theradio strength measuring means of the mobile station and the position ofthe mobile station at the measuring point inputted from the input meansand for storing the learned correlation therebetween, and positionestimation processing means for estimating the position of the mobilestation at the measuring time on the basis of the reception radiostrength levels from the plurality of base stations measured by themobile station at an arbitrary point through the use of the correlationthe position learning processing means learns. This system can realize aposition detection method in which the mobile station takes in its ownposition through the operation by the user or through a differentposition detection device in addition to the measured reception radiostrength levels and the control station learns using these data.

Furthermore, the control station is equipped with radio strength reportrequesting means for transmitting a radio strength report requestingmessage to the mobile station so that the mobile station measures thereception radio strength levels from the plurality of base stations andreports the measurement results thereto. Accordingly, the controlstation can request the radio strength measurement data from anarbitrary mobile station when necessary. Still further, the mobilestation is equipped with self mobile station position inquiry means forissuing a measurement request for radio strength levels to the radiostrength measuring means, and when receiving the reception radiostrength levels measured by the radio strength measuring means, thecontrol station estimates the position of the mobile station and informsthe mobile station of the estimation result. In this system, the user ofthe mobile station can operate the self mobile station position inquirymeans to inquire to the control station for its own present position. Inaddition, the mobile station is provided with different mobile stationposition inquiry means for transmitting a request for the inquiry forthe position of a different mobile station to the control station, andwhen the control station receives this request, the radio strengthreport requesting means issues a radio strength report request messageto the different mobile station whose position is inquired and, inresponse to the report on the measurement result of the radio strengthlevels from the different mobile station, the control station estimatesthe position of the different mobile station on the basis of measurementresult to inform the mobile station, which made the inquiry, of theestimation result. According to this system, the user who carries themobile station can operate the different mobile station position inquirymeans to inquire to the control station for the position of the personwho carries the different mobile station.

Moreover, the control station is equipped with position accumulationmeans for accumulating the information on the positions of the mobilestation estimated in the position estimation processing means in timeseries and history decision means for deciding, on the basis of thetransition of the position of the mobile station with time accumulatedin the position accumulation means, whether the position of the mobilestation estimated by the position estimation processing means isappropriate or not. If the history decision means makes a decision tothat it is not appropriate, the radio strength report requesting meanstransmits the radio strength report requiring message to the mobilestation. According to this system, in the case that an inproperestimation result arises due to a large variation of the electric fielddistribution of the base station, the measurement is resumed, thusenhancing the accuracy of the estimation result.

In addition, the mobile station is equipped with at least two frequencysynthesizers, and even if one frequency synthesizer synchronizes with acommunication carrier at the call, the radio strength measuring meansmeasures the radio strength levels from a plurality of base stationsthrough the use of the other frequency synthesizer. Thus, the mobilestation can perform the measurements of the reception radio radiostrength levels irrespective of the call. Further, the control stationis provided with distance calculation means for calculating the distancebetween the mobile station and each of the base stations as a functionof of the reception radio strength levels from a plurality of basestations measured by the mobile station through the use of a theoreticalelectric field strength distance characteristic obtainable from theoutputs and frequencies of the base stations, and the position learningprocessing means learn, through a neural network, the correlationbetween the calculated distance and the position of the measuring point.This system permits the position estimation with a high accuracy throughthe use of the calculated theoretical distance for the learning.

Furthermore, the mobile station is equipped with learning result storagemeans for storing the parameters for a neural network conveyed from thecontrol station and position calculation means for constructing a neuralnetwork using the parameters stored in the learning result storage meansto detect its own position on the basis of the reception radio strengthlevels from a plurality of base stations measured at an arbitrary pointthrough the use of the constructed neural network. This system can adoptthe above-mentioned position detection method in which the mobilestation detects its own position without the inquiry to the controlstation. Still further, the control station learns the correlationbetween the reception radio strength levels and the area in which themobile station stands, through a neural network including nodes of aninput layer accepting the reception radio strength levels from aplurality of base stations and nodes of an output layer corresponding innumber to the areas defining the range of an object under detection suchas a room and a zone. This system can conduct the above-mentionedposition detection method which detects the room or zone where a personcarrying the mobile station exists or presents a plurality of places asthe candidates for the person's whereabouts.

Moreover, in a wireless radiocommunication system equipped with a mobilestation, base stations and a control station and made such that thecontrol station detects the position of the mobile station, each of thebase stations is provided with radio strength measuring means formeasuring the reception radio strength level from the mobile station,while the control station is equipped with position input means foraccepting the position of a measuring point, position learningprocessing means for learning, through a neural network, the correlationbetween the reception radio strength level of the radio wave emittedfrom the mobile station at the measuring point and measured by the basestation and the position of the measuring point inputted through theposition input means, and position estimation processing means forestimating the position of the mobile station on the basis of thereception radio strength level from the mobile station measured by eachof the base stations through the use of the correlation the positionlearning processing means learns. This system can introduce theabove-mentioned position detection method in which a plurality of basestations measure the radio wave from the mobile station to detect theposition of the mobile station.

In addition, in a mobile station position detection method according tothis invention, the radio strength levels from a plurality of basestations at a measuring point within a service area are measured pluraltimes and accumulated in a radio strength data storage section whichmakes a corresponding relation (mapping) between the reception radiostrength levels and a position expressible with a continuous value suchas coordinate, and the reception radio strength levels in the radiostrength data storage section are compared with reception radio strengthlevels at a position detecting point at the time of the positiondetection, and when a position detection section estimates the positionof the mobile station by introducing such a statistic method as tocalculate a weighted mean of a plurality of radio strength data that theradio strength level comparison result shows a small error. Accordingly,the estimated position is not limited to the actual measurement pointand the position of the mobile station can be estimated within a rangesmaller than a distance between the measuring points.

Furthermore, of the reception radio strength levels and the positioncoordinates accumulated in a radio strength data storage section, theposition coordinates are accumulated as a position expressible with adiscrete value, and the radio strength data in the radio strength datastorage section are compared with the reception radio strength levels atthe position detection so that the position of the mobile station isestimated by employing a statistic method in which, for example, aposition detection control section makes a majority decision using aplurality of radio strength data that the radio strength comparisonresult shows a small error, and the degree of the reliability of theposition detection is found through, for example, a statistic method touse the rate of the estimated position to a plurality of extracted radiostrength data.

According to this invention, a wireless radiocommunication system whichperforms radiocommunications between a mobile station and a base stationis equipped with radio strength data storage section for retainingpositional information on a plurality of measuring points expressiblewith continuous values and radio strength data including reception radiostrength levels from a plurality of base stations at the respectivemeasuring points, a position detection section having means forcomparing the radio strength data in the radio strength data storagesection with radio strength levels at a position detecting point toestimate the position, an error radio strength data storage section forholding a plurality of radio strength data involving a small error onthe comparison in the position detection section, and the positiondetection section performs the position detection using the plurality ofradio strength data in the error radio strength data storage section.Thus, the estimated position is not limited to the actual measuringpoint but the position can be estimated with a range smaller than theinterval between the measuring points.

Furthermore, according to this invention, a wireless radiocommunicationsystem which performs radiocommunications between a mobile station and abase station is equipped with radio strength data storage section forretaining positional information on a plurality of measuring pointsexpressible with discrete values and radio strength data includingreception radio strength levels from a plurality of base stations at therespective measuring points, a position detection section having meansfor comparing the radio strength data in the radio strength data storagesection with radio strength levels at a position detecting point toestimate the position, an error radio strength data storage section forholding a plurality of radio strength data which produce a small errorin the comparison in the position detection section, and the positiondetection section performs the position detection expressible with thediscrete values, using the plurality of radio strength data in the errorradio strength data storage section. At the position detection, theradio strength data in the radio strength storage section is comparedwith the reception radio strength levels taken for the positiondetection, and a position detection control section estimates theposition by, for example, employing a statistic method to make amajority decision on the plurality of radio strength data in the errorradio strength data storage section which make a small comparison errorand further estimates the degree of the reliability of the obtainedposition by, for example, employing a statistic method to calculate therate of the estimated position to the plurality of radio strength data.

In addition to these arrangements, a position detection knowledgesection is provided which has a knowledge on a person carrying themobile station and an action rule or schedule of that person, and theposition detection section carries out the position detection throughthe use of the plurality of radio strength data in the error radiostrength data storage section and the knowledge in the positiondetection knowledge section. Because of using the knowledge on a personand an action rule and schedule of that person at the positionestimation, it is possible to remove data with a low possibility ofmovements such as the inhibition of entry into a room but to select datawith a high possibility of movements, with the result that the positiondetection can improve in accuracy.

Furthermore, a position detection knowledge section is provided whichhas knowledge on the relationship between a plurality of positionsexpressible with discrete values, and the position detection sectionconducts the position detection using a plurality of radio strength datain the error radio strength data storage section and the knowledge inthe position detection knowledge section. Through the use of theknowledge on the relationship between the plurality of positionsexpressible with discrete values, it is possible to exclude, of theplurality of radio strength data held in the error radio strength datastorage section, the data remote in connection, and it is possible todecide whether or not it corresponds to the vicinity of the boundarybetween rooms, thus developing the position detection accuracy.

Still further, the position detection is conducted in such a manner thatthe number of radio strength data held in the error radio strength datastorage section is changed in accordance with the degree of the errorbetween the radio strength levels at the position detecting point andthe radio strength data in the radio strength data storage section.Since the number of the radio strength data in the error radio strengthdata storage section varies in accordance with the degree of the error,the improvement of the position detection accuracy is possible.

Moreover, the position detection section is equipped with a positionaccumulation section for accumulating short-term positions the positiondetection section estimates in the past and a history decision sectionfor deciding the appropriateness of the estimated position on the basisof the radio strength data held in the error radio strength data storagesection. The appropriateness of the estimated position is judged in amanner that the moving situation is decided on the basis of the latestestimated position of the mobile station in the past and that time andfurther the present position and the time at that position. If notappropriate, the position detection is again conducted. Since the movingspeed or the locus is calculated on the basis of the short-term historyto decide the appropriateness of the estimated position, the positiondetection can improve in accuracy.

In addition, in place of accumulating the short-term positions estimatedin the past, a long-term history is established and held by accumulatingthe past experiences such as the places to which the mobile station hasmoved in the past and the frequency of the movements in the short termsto decide, on the basis of the past movement experiences of the mobilestation, whether the estimated position is appropriate or not. If notappropriate, the position detection is again conducted. Since theappropriateness of the position estimated by the possible movement rangeof the mobile station on the past experiences of the mobile station isjudged from the long-term history, the improvement of the positiondetection accuracy is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

The object and features of the present invention will become morereadily apparent from the following detailed description of thepreferred embodiments taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a block diagram showing an arrangement of a radiocommunicationsystem which adopts a position detection method according to a firstembodiment of the present invention;

FIG. 2 is an illustration of an image of the radiocommunication systembased upon the position detection method according to the firstembodiment;

FIG. 3 shows an example of a structure of a neural network to be used ina position learning processing section of the radiocommunication systemfor the position detection method according to the first embodiment;

FIG. 4 is an arrangement of a radiocommunication system which introducesa position detection method according to a second embodiment of thisinvention;

FIG. 5 is an arrangement of a radiocommunication system which adopts aposition detection method according to a third embodiment of thisinvention;

FIG. 6 is an arrangement of a radiocommunication system which follows aposition detection method according to a fourth embodiment of thisinvention;

FIG. 7 is an arrangement of a radiocommunication system which adopts aposition detection method according to a fifth embodiment of thisinvention;

FIG. 8 is an arrangement of a radiocommunication system for a positiondetection method according to a sixth embodiment of this invention;

FIG. 9 is an arrangement of a radiocommunication system which introducesa position detection method according to a seventh embodiment of thisinvention;

FIG. 10 is an arrangement of a radiocommunication system based upon aposition detection method according to an eighth embodiment of thisinvention;

FIG. 11 is a block diagram showing an arrangement of aradiocommunication system based upon a position detection methodaccording to a ninth embodiment of this invention;

FIG. 12 is a block diagram showing an arrangement of a positiondetection system in a radiocommunication system adopting the positiondetection method according to the ninth embodiment;

FIG. 13 is an illustration of an image of a radiocommunication systembased upon the position detection method according to the ninthembodiment;

FIG. 14A is a flow chart showing a position detection process in aradiocommunication system adopting the position detection methodaccording to the ninth embodiment;

FIG. 14B is a flow chart showing a principal portion of the positiondetection process in the radiocommunication system adopting the positiondetection method according to the ninth embodiment;

FIG. 15 is a block diagram showing an arrangement of a positiondetection system in a radiocommunication system based upon a positiondetection method according to a tenth embodiment of this invention;

FIG. 16 shows an example of the layout of rooms in which aradiocommunication system adopting the position detection methodaccording to the tenth embodiment accomplishes a position detection;

FIG. 17 illustrates an example of a meeting room reservation systemconnected to a radiocommunication system adopting the position detectionmethod according to the tenth embodiment;

FIG. 18 is a graphic illustration of connections between rooms in aradiocommunication system adopting the position detection methodaccording to the tenth embodiment;

FIG. 19 is a block diagram showing an arrangement of a positiondetection system in a radiocommunication system based upon a positiondetection method according to an eleventh embodiment of this invention;

FIG. 20 shows an arrangement of a radiocommunication system which adoptsa prior position detection method; and

FIG. 21 shows an arrangement of a radiocommunication system based upon aprior position detection method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, a description will be made hereinbelow ofembodiments of the present invention.

First Embodiment

A mobile station position detection method according to a firstembodiment of this invention is such that the relationship between theradio strength levels from a plurality of base stations and the positionof a mobile station is learned through a neural network to estimate theposition of the mobile station on the basis of the radio strength levelsmeasured by the mobile station. In a radiocommunication system whichintroduces this detection method according to the first embodiment is,as shown in FIG. 1, a mobile station 101 is composed of a mobile stationcontrol section 102 for controlling the operation of the mobile station101, a radio strength measuring section 103 for measuring the radiostrength level of a signal from a base station(s) and a mobile stationtransmission and reception section 104 for signal transmission andreception, and a base station 105 is made up of a base station controlsection 106 for controlling the operation of the base station 106, abase station transmission and reception section 107 for signaltransmission and reception to and from the mobile station 101, and abase station input and output section 108 for signal transmission andreception to and from a control station 111 through a wire line, andfurther the control station 111 is equipped with a control stationcontrol section 112 for controlling the operation of the control station111, a communication control section 113 for controlling thecommunication with the base station 105, a position input section 114for undergoing the input of coordinate data on a radio strengthmeasuring point, position learning processing section 115 for learning,through a neural network, the correlation between the position of themobile station 101 and the reception radio strength level at that pointand for storing the correlation therebetween, and a position estimationprocessing section 116 for estimating the position of the mobile station101 on the basis of the measured radio strength level through the use ofthe stored correlation. In FIG. 1, numerals 109 and 110 representdifferent base stations each having the same arrangement as that of thebase station 105.

FIG. 2 shows a system image of this radiocommunication system. Thesystem comprises a mobile station 201, base stations 202, 203, 204respectively having radio zones 205, 206, 207, and a control station 208equipped with a position input section 209, a position learningprocessing section 210 and a position estimation processing section 211.In this system, in cases where as shown in FIG. 2 the mobile station 201simultaneously stands within the radio zones 205, 206, 207 of theplurality of base stations 202, 203, 204, the detection of the positionof the mobile station 201 is made on the basis of the strength levels ofthe radio waves from the base stations 202, 203, 204, measured by themobile station 201, by means of the functions of the position inputsection 209, the position learning processing section 210 and theposition estimation processing section 211 belonging to the controlstation 208.

For the position detection of the mobile station, the operation of thesystem comprises two modes: a learning mode and an estimation mode. Inthe learning mode, the position coordinates corresponding to a pluralityof predetermined measuring points are inputted through the positioninput section 114 of the control station 111 and stored in the positionlearning processing section 115. At this time, numbers indicative of theorder of the measurements are assigned to the measuring points, and thecoordinate system representative of the positions of the measuringpoints is singly determined in areas where the position detection ismade. When the information on the measuring points are conveyed throughsome means to the mobile station 101 side, if the measuring points areindicated with points on a map, the mobile station 101 is transferred tothe indicated points in the order of measurements, i.e., in the order ofthe numbers of the measuring points, where the mobile stationtransmission and reception section 104 receives radio waves from thebase stations 105, 109 and 110 and the radio strength measuring section103 measures the reception radio strength levels of the signalstherefrom. The mobile station transmission and reception section 104transmits the measurement data to the base station 105 which producesthe highest radio strength level.

When in the base station 105 the base station transmission and receptionsection 107 receives the reception radio strength data from the mobilestation 101, the base station control section 108 decides the kind ofdata and transmits it through the input and output section 108 to thecontrol station 111. In the control station 111, the communicationcontrol section 113 receives the reception radio strength data from themobile station 101 through the base station 105 and the control stationcontrol section 112 decides the reception of the reception radiostrength data and hands it over to the position learning processingsection 115. Thus, the reception radio strength data are communicatedfrom the mobile station 101 to the position learning processing section115 in the order of measurements, so that the correspondence (mapping)is made between the position coordinates of the respective measuringpoints inputted in advance through the position input section 114 andthe reception radio strength data from the mobile station 101 at therespective measuring points.

The learning in the position learning processing section 115 is madethrough the use of a neural network, for example, as shown in FIG. 3. InFIG. 3, numeral 301 represents an input layer, numeral 302 depicts anintermediate layer and numeral 303 denotes an output layer. This neuralnetwork has a layered perceptron structure made such that, when thereception radio strength levels due to base stations from a mobilestation are inputted into the nodes of the input layer 301, the positioncoordinates of the mobile station at that measuring point are outputtedfrom the output layer 303. In this neural network, appropriatecontinuous functions such as the sigmoid functions are used as the inputand output functions for the nodes. This neural network is not a specialneural network but is well known as being written as a typical examplein the references, and the detailed description thereof will be omittedfor brevity. As the references, there are “Mathematical Theory of NeuralNetworks” published by Sangyo Tosho (1978), written by Shunichi AMARIand “Information Processing of Neural Network” published by Sangyo Tosho(1988), written by Hideki ASO.

In the position learning processing section 115, the positioncoordinates of the measuring points and the reception radio strengthlevels in the mobile station 101 at the measuring points, which are madein the corresponding relation to each other, are used as the learningdata for the neural network (in this case, the reception radio strengthlevels serve as the input signals and the position coordinates act asthe teacher signals). First, the reception radio strength levels due toa plurality of base stations in the mobile station 101 standing at themeasuring point are inputted into the nodes of the input layer 301,respectively. At this time, the neural network learns so that the outputvalues from the nodes of the output layer 303 after passing through theintermediate layer 302 coincide with the position coordinates of themeasuring point. More specifically, the weights on connections betweenthe nodes of the input layer 301 and the nodes of the intermediate layer302 and the weights on connections between the nodes of the intermediatelayer 302 and the nodes of the output layer 303 are adjusted to reducethe error between the actual outputs (the values of the outputs of theoutput layer 303 when the input layer 301 receives the radio strengthvalues) and the correct position coordinates. This learning rule isgenerally referred to as a back propagation, but this embodiment is notlimited to this method. The details about the learning rules are alsowell known, and the description thereof will be omitted (see theabove-mentioned references).

In terms of all the measuring points, through the input of the receptionradio strength levels due to the respective base stations in the mobilestation 101, the learning for the output of the position coordinates ismade till the convergence (for example, the convergence condition isthat the sum of errors at each of the measuring points comes to below agiven value). After the completion of the learning, the positionlearning processing section 115 passes the weights on connection betweenthe input layer 301 and the intermediate layer 302 the the weights onconnections between the intermediate layer 302 and the output layer 303to the position estimation processing section 116 which in turn, storesthem. This is the operations in the learning mode.

In the estimation mode, the actual position detection function workshere to estimate the present position of the mobile station. In themobile station 101, the mobile station transmission and receptionsection 104 receives receivable radio wave signals from a plurality ofbase stations at a timing according to the input instructions from theuser at an arbitrary point, at an operational timing on the system or ata constant time interval. Subsequently, the radio strength measuringsection 103 measures the radio wave signals therefrom (the reception andmeasurement timings are under the control of the mobile station controlsection 102), and the transmission and reception section 103 transmitsthis reception radio strength data to, for example, the selected basestation 105 which causes the highest radio strength level. In the basestation 105, the base station transmission and reception section 107receives the reception radio strength data from the mobile station 101,while the base station control section 106 judges the kind of data andsends it through the input and output section 108 to the control station111.

In the control station 111, the communication control section 113receives the radio strength data from the mobile station 101 through thebase station 105 and the control station control section 112 decides thereception thereof and hands it over to the position estimationprocessing section 116. The position estimation processing section 116constructs a neural network with the same structure as that of theneural network used at the learning on the basis of the weights onconnections fed from the position learning processing section 115.Further, the reception radio strength data due to the plurality of basestations in the mobile station 101 are inputted to the constructedneural network to obtain as outputs the position coordinates of themobile station 101 at the time that the mobile station 101 measures andreports the reception radio strength levels. Thus, the positionestimation processing section 116 estimates and detects the position ofthe mobile station 101 on the basis of the reception radio strengthlevels due to the plurality of base stations in the mobile station 101.The accuracy of the position detection depends upon the learning resultin the learning mode, and in general, on the learning characteristic ofthe neural network, the accuracy thereof can improve in such a manner asto increase the number of measuring points or the number of times ofmeasurements at the measuring points in the learning mode.

Although in the above description the operation of theradiocommunication system is divided into the learning mode and theestimation mode, it is also possible that the control station 111 makesthe switching between these operational modes in a clear expression orthe control station control section 112 switches the operation inaccordance with the kind of data in a state where the mode informationindicative of the kind of data is added to the reception radio strengthdata the mobile station 101 reports. Further, although the mobilestation used in the learning mode and the mobile station used in theestimation mode are described as the mobile station 101 in FIG. 1, thereis no need for these mobile stations being the same.

Second Embodiment

A description will be made hereinbelow of a position detection method ofa radio mobile station according to a second embodiment of thisinvention. This detection method is to make a neural network learn in away that the position of a charger for the mobile station is treated asa measuring point. A radiocommunication system based on this detectionmethod is, as shown in FIG. 4, equipped with mobile stations 401, 402,403, chargers 404, 405, 406 for charging the mobile stations 401, 402,403, base stations 407, 408, 409, and a control station 410. The controlstation 410 is made up of a measurement position storage section 411 forstoring the positional information on the measuring points predeterminedin position, a position learning processing section 412 for learning,through a neural network, the correlation between the measuring pointsthe reception radio strength levels at the measuring points and forstoring the correlation therebetween, and a position estimationprocessing section 413 for estimating the position of the mobile stationon the basis of the measured radio strength values through the use ofthe correlation. In FIG. 4, numeral 414 designates a coordinate system.

This system is made taking into consideration the case that the chargersare fixedly disposed at predetermined positions, for example, the casethat a charger is fixedly placed on a disk of each person in a firm. Inthis case, the positions of the respective chargers are expressed withthe predetermined coordinate system 414 (the coordinate system canfreely be set), and the position coordinates thereof are stored in themeasurement position storage section 411 of the control station 410.Now, let it be assumed that the mobile stations 401, 402, 403simultaneously exist within the radio zones of the base stations 407,408, 409 and are set on the arbitrary chargers 404, 405, 406,respectively. At this time, the mobile stations 401, 402, 403 detectthat they are in the charged conditions, and obtain the chargeridentification information from the chargers 404, 405, 406,respectively, and further measure the reception radio strength levelsfrom the base stations 407, 408, 409.

Secondly, the mobile stations 401, 402, 403 reports the chargeridentification information and the reception radio strength levels fromthe base stations 407, 408, 409 through one of the base stations 407,408, 409 to the control station 410. In response to the reporttherefrom, in the control station 410, the position learning processingsection 412 obtains the position coordinates corresponding to thereception radio strength levels measured and reported by the mobilestations 407, 408, 409 referring to the positional information on allthe chargers stored in advance in the measurement position storagesection 411, i.e., the position coordinates expressed by the coordinatesystem 414. Further, as well as the first embodiment, for the learning aneural network is constructed which receives as inputs the receptionradio strength levels from the respective base stations at each positionand outputs the corresponding position coordinates, and the weights onconnections between the nodes in the neural network are stored as thelearning results in the position estimation processing section 413.

In this way, for collecting the data for learning of the correlationbetween the reception radio strength levels from the plurality of basestations in the mobile stations and the positions of the mobilestations, the plurality of mobile stations are used and the receptionradio strength levels therefrom are measured at the known positions ofthe chargers. Accordingly, it is possible to simplify the input of theposition coordinates of the measuring points. In addition, since themeasurements of the reception radio strength levels are always possiblewhile the mobile stations are in the charged conditions, it is possibleto collect large amount of data, thus enhancing the position detectionaccuracy.

Although in this embodiment the positions of the chargers are fixed toobtain the position coordinates of the measuring points for the learningdata (reception radio strength levels), if the correspondence betweenthe chargers and the mobile stations is made in advance, it is alsopossible to adopt a method of specifying the mobile station learningdata measuring point without obtain the identification information fromthe chargers or a method of determining the learning data measuringpoint at every mobile station. Further, it is also appropriate that, forcollecting the learning data, on the measuring point there are provideda learning data collector equipped with only a radio strength measuringsection for measuring the reception radio strength levels from aplurality of base stations and a transmission and reception section fortransmitting the reception radio strength levels through the basestation to the control station and further for receiving a controlsignal from the control station. In this embodiment, the operation ofthe radiocommunication system in the position estimation mode is thesame as that in the position estimation mode in the first embodiment.

Third Embodiment

Furthermore, a description will be taken hereinbelow of a positiondetection method of a radio mobile station according to a thirdembodiment of this invention. The third embodiment provides a radiomobile station position detection method in which the user carrying amobile station finds, through the mobile station, its own presentlocation or the position of a different mobile station.

In a radiocommunication system adopting this detection method, as shownin FIG. 5 mobile stations A501, B507 are equipped with mobile stationcontrol sections 502, 508 for controlling the operations of the mobilestations A501, B507, radio strength measuring sections 503, 509 formeasuring the radio strength levels of signals received from basestations, mobile station transmission and reception sections 506, 512for conducting transmission and reception of signals to and from thebase stations, position input sections 504, 510 for allowing the user toinput learning data measuring positions, and position inquiry sections505, 511, while a control station 516 is provided with a control stationcontrol section 517 for taking charge of the control of the operation ofthe control station 516, a communication control section 518 forcontrolling the communications with the base stations, a radio strengthreport requesting section 520 for making a request for the radiostrength levels to the mobile stations 501, 507, a position learningprocessing section 519 for learning, through a neural network, thecorrelation between the locations of the mobiles stations 501, 507 andthe reception radio strength levels at the mobile station locations andfurther for storing the correlation therebetween, and a positionestimation processing section 521 for estimating the position of themobile stations 501, 507 on the basis of the measured radio strengthvalues through the use of the stored correlation. The arrangement ofeach of base stations 513, 514, 515 is the same as that of the basestation in the first embodiment (see FIG. 1).

First, a description will be taken hereinbelow of the operation of thissystem in a learning mode. The user carrying the mobile station A501inputs positional information through the position input section 504 ata learning data measuring position. Subsequently, the mobile stationcontrol section 502 detects the input and gives instructions to theradio strength measuring section 503 to measure the receivable radiostrength levels from all the base stations including the plurality ofbase stations 513, 514, 515 (similarly, measuring the radio strengthlevels from the mobile station B). After the measurements, the radiostrength measuring section 503 transmits the measured reception radiostrength levels from the plurality of base stations and the positionalinformation on the measuring points through the transmission andreception section 506 to the base station 513 which caused the highestreception radio strength level, while the base station 513 communicatesthese data to the control station 516.

In the control station 516, the communication control section 518receives these data, whereas the control section 517 judges the kind ofdata and conveys these data to the position learning processing section519. With this process, the data for the learning of the neural networkare collected in the position learning processing section 519. Theoperation of the position learning processing section 519 subsequentlyconducted is the same as those of the position learning processingsections of the radiocommunication systems according to the first andsecond embodiments.

Secondly, the description proceeds to an operation in an estimationmode. In this instance, let it be assumed that the user of the mobilestation A501 tries to find its own position or the position of themobile station B507 being a different mobile station. The user of themobile station A 501 first, when wanting its own position, givesinstructions therefor to the position inquiry section 505 and, whenwanting the position of the other mobile station B, inputs theidentification number (telephone number or the like) for the mobilestation B to make an inquiry. In the case of giving instructions for theinquiry on its own position, the position inquiry section 505 asks themobile station control section 502 to give instructions to the radiostrength measuring section 503 to measure the reception radio strengthlevels from all the base stations. After the measurements, the radiostrength measuring section 503 conveys the measurement results throughthe base station 513 to the control station 516.

In the control station 516, the communication control section 518receives the measurement results and passes them to the positionestimation processing section 521. The position estimation processingsection 521 inputs the reception radio strength levels on the pluralityof base stations reported from the mobile station A501 to the neuralnetwork which already completed the learning in the position learningprocessing section 519 to obtain the corresponding position coordinates.The position coordinates thus obtained are delivered to thecommunication control section 518 to be transmitted through the basestation 513 to the mobile station 501, so that the mobile station A501can find its own present location.

On the other hand, in the case that in the mobile station A theinstructions for the position of the mobile station B, together with theidentification number of the mobile station B, are given, the positioninquiry section 505 gives instructions to the transmission and receptionsection 506 to transmit the inquiry request and the identificationnumber of the target mobile station through the base station 513 to thecontrol station 516. In the control station 516, the communicationcontrol section 518 receives these information and the control section517 analyzes the reception data to make a decision to that it is aninquiry request for the position of the mobile station B and hands thedata over to the radio strength report requesting section 520. Whenreceiving the data, i.e., the identification number of the mobilestation B and the inquiry request for the position thereof, the radiostrength report requesting section 520 issues a radio strength reportrequest on the mobile station B to the communication control section518. The communication control section 518, which performs the movementmanagements (the functions provided in the standards for the portabletelephones or PHSs) on the position registration of the mobile stations,retrieves the general calling area (an area comprising the radio zonesof a plurality of base stations for the general calling, which allowsthe transmission to the mobile station) for the mobile station B507 andtransmits the radio strength report request to the mobile station B507.

When the mobile station B507 receives the radio strength report request,the radio strength measuring section 509 measures the reception radiostrength levels from all the base stations receivable and reports themthrough an appropriate base station to the control station 516. Inresponse to the radio strength report from the mobile station B507, inthe control station 516 the position estimation processing section 515obtains the position of the mobile station B517 and the communicationcontrol section 518 transmits it to the mobile station A501. Thus, themobile station A501 can find the location of the mobile station B507.

In any case, a method of displaying to the user its own or differentmobile station position coordinate data is not limited, and methods areavailable to display the data as values and display the data in themanner of plotting them on a map image.

Fourth Embodiment

Furthermore, a description will be taken hereinbelow of a positiondetection method of a radio mobile station according to a fourthembodiment of this invention. The radio mobile station positiondetection method according to the fourth embodiment is for improving theaccuracy of the position detection in a manner of doing the measurementsover again when the estimation result shows a low reliability. In aradiocommunication system introducing this detection method, as shown inFIG. 6 a control station 608 includes a control station control section609 for controlling the operation of the control station 608, acommunication control section 610 for controlling the communication withbase stations, a position input section 611 for accepting the positionof a measuring point, a position learning processing section 612 forlearning, through a neural network, the correlation between the positionof a mobile station and reception radio strength levels at that positionand further for storing the correlation therebetween, a positionestimation processing section 613 for estimating the position of themobile station on the basis of the measured radio strength levelsthrough the use of the correlation therebetween, a radio strength reportrequesting section 614 for making a request for the report on the radiostrength levels to the mobile station, a position accumulation section615 for accumulating the past position coordinates of the mobilestation, and a history decision section 616 for deciding, on the basisof the past positions, whether the estimated present position of themobile station is appropriate or not. The arrangements of a mobilestation 601 and each of mobile stations 605, 606, 607 are the same asthose in the first embodiment (see FIG. 1).

The operation of this system in the learning mode is the same as that inthe first embodiment, whereas in the estimation mode the system operatesas follows. That is, in the control station 608, the positionaccumulation section 615 stores the position coordinates of all themobile stations obtained by the position estimation processing section613 in the past as time series data at every mobile station, togetherwith the time stamp. When the mobile station 601 reports the receptionradio strength levels from a plurality of base stations measured by theradio strength measuring section 603 through the base station 605 to thecontrol station 608 in some occasion, the communication control section610 of the control station 608 receives this report, and the controlsection 609 decides the kind of data and conveys it to the positionestimation processing section 613.

The position estimation processing section 613 obtains the positioncoordinates of the mobile station 601 on the basis of the reportedreception radio strength levels due to the plurality of base stationsthrough the use of the neural network which completed the learning inthe position learning processing section 612 and passes them to thehistory decision section 616. The history decision section 616 refers tothe past position coordinates of the mobile station 616 accumulated inthe position accumulation section 615 to decide whether the presentposition of the mobile station 610 estimated in the position estimationprocessing section 613 is proper or not. For the decision criterion,various ways can be taken. For example, a method is available tocalculate the moving speed on the basis of the position obtained throughthe last estimation and the time of the estimation and the presentposition and the present time to decide whether or not the calculatedspeed is appropriate for the user carrying the mobile station or to drawthe locus of the past position history to decide the appropriateness onthe basis of the degree (an angle of a moving vector or the like) of thedeviation in the moving direction indicated by the locus. However, thisembodiment is not limited to these methods.

If appropriate, this coordinates is determined as the present positionof the mobile station 601 and outputted from the position estimationprocessing section 613 (the destination may be a display unit of thecontrol station, the mobile station 601, a different mobile station orthe like). On the other hand, if not appropriate, the history decisionsection 616 gives instructions to the radio strength report requestingsection 614 to issue a radio strength report request toward the mobilestation 601. The radio strength report requesting section 614 transmitsthe radio strength report request to the mobile station 601 so that themobile station 601 again measures the receivable radio strength levelsfrom all the base stations and reports the measurement results. Whenreceiving this request through the base station 605, in the mobilestation 601 the radio strength measuring section 603 measures thereceivable radio strength levels from all the base stations and reportsthe measurement results to the control station 608. In the controlstation 608, the position estimation processing section 613 finds thelocation of the mobile station 601 and the history decision section 616judges the appropriateness of the coordinate values. If not appropriate,the above-mentioned procedure is repeated. However, in this instance, itis necessary to determine the upper limit on the number of times ofrepetition of the radio strength report request to the mobile station601 in advance. In the case that the decision of no appropriatenesscontinues, the estimation of the position resumes the limited number oftimes of the repetition and then stops. In this case, the position isdetermined in such a way that the most appropriate value is adopted orthe values estimated so far are averaged.

As described above, in the position detection method according to thisembodiment, in cases where, for example, a great variation of theelectric field distribution in the base stations of a radiocommunicationsystem or the learning accuracy is insufficient so that the reliabilityof the accuracy of position of the mobile station obtained in theposition estimation processing section is expected to be low, themeasurement in the mobile station resumes to repeatedly conduct theposition estimation, with the result that the accuracy and reliabilityof the position detection can improve.

In addition, it is also appropriate that in this system a measurementinterval measuring section is provided in the mobile station 601, andthe radio strength measuring section 603 measures the radio strengthlevels from a plurality of base stations at a constant time intervalmeasured by the measurement interval measuring section to report themeasurement results through the base station to the control station 608.In this instance, since it is possible to establish the history on theposition of the mobile station at the constant time interval, and henceit is possible to more accurately judge the appropriateness of theestimated position coordinates of the mobile station.

Fifth Embodiment

Still further, a description will be taken hereinbelow of a positiondetection method of a radio mobile station according to a fifthembodiment of this invention. This radio mobile station positiondetection method according to the fifth embodiment is made such that theradio strength levels measured is converted into the distance betweenthe mobile station and the base stations and the neural network learnson the basis of the distance therebetween.

In a radiocommunication system conducting this detection method, asshown in FIG. 7 a control station 708 is provided with a control stationcontrol section 709 for taking charge of the control of the controlstation 708, a communication control section 710 for controlling thecommunication with base stations, a position input section 711 foraccepting the input of the positions of measuring points, a positionlearning processing section 712 for learning, through a neural network,the correlation between the position of a mobile station and thereception radio strength levels at that position and further for storingthe correlation therebetween, a position estimation processing section713 for estimating the position of the mobile station on the basis ofthe measured reception radio strength levels through the use of thecorrelation therebetween, and a distance calculation section 714 fortheoretically calculating the distance between the mobile station andthe base stations. In this system, the arrangements of a mobile station701 and each of base stations 705, 706, 707 are the same as those in thefirst embodiment (see FIG. 1).

In this system, the distance calculation section 714 of the controlstation 708 stores a theoretical radio distance characteristic (thissignifies the relationship between the distance from the base stationand the radio strength level therefrom and under an ideal condition theradio strength attenuates in inverse proportion to the square ofdistance therefrom) of the base station and calculates the theoreticaldistances between the mobile station 701 and the plurality of basestations 705, 706, 707 on the basis of the reception radio strengthlevels due to the base stations 705, 706, 707 reported from the mobilestation 701 through the use of the stored radio distance characteristic.Further, the distance calculation section 714 outputs the distance tothe position learning processing section 712 in the learning mode andoutputs it to the position estimation processing section 713 in theestimation mode (if the theoretical distance coincides with the actualdistance, the specification of the position of the mobile station ispossible with only a geometric calculation. However, in fact they hardlycoincide with each other because of the influence from the reflectionwaves or noises. Thus, the position learning processing section 712 isrequired to learn the deviation from the theoretical distance).

In the learning mode, the position learning processing section 712learns, through a neural network, the correlation between thetheoretical distance from the mobile station 701 to each of the basestations, conveyed from the distance calculation section 714, and thelearning measuring point position coordinates of the mobile station 701inputted through the position input section 711 as well as the firstembodiment and communicates the connection weights of the neural networkbeing the learning results to the position estimation processing section713 which in turn, stores them. On the other hand, in the estimationmode, the position estimation processing section 713 inputs thetheoretical distance from each of the base stations to the mobilestation 701 conveyed from the distance calculation section 714 to anetwork constructed using the connection weights undergoing the learningto obtain the position coordinates of the mobile station 701 as anoutput. Thus, the theoretical knowledge is introduced for the learningin the position learning processing section 713, and as compared withthe first embodiment, the learning processing conducted through theneural network becomes easier and the learning accuracy more improves.

As described before, in the mobile station position detection methodaccording to this embodiment, the theoretical distance between themobile station and each of the base stations is calculated as a functionof the reception radio strength levels from the plurality of basestations measured in the mobile station, and the correlation between thetheoretical distance and the position of the mobile station is learnedthrough the neural network, thus estimating the position of the mobilestation through the use of the correlation. With this operation, theposition estimation with a higher accuracy is possible as compared withthe first embodiment.

Furthermore, the embodiments described above can appropriately acceptthe changes. For example, in cases where the mobile station outputs themeasurement results on the reception radio strength levels, it is alsoappropriate that the measurement is made plural times at the same pointso that the single value obtained through the statistical processing ofthe measurement values is outputted as the final measurement value. Thisstatistical processing permits the sharp improvement of the measurementaccuracy. Still further, it is also possible that two frequencysynthesizers are provided in the mobile station so that, even if one ofthe frequency synthesizers is in the synchronized condition during acall, the measurement of the radio strength levels from a plurality ofbase stations is possible through the use of the other frequencysynthesizer.

In addition, it is also possible that the mobile station sends themeasurement results on the reception radio strength levels to thecontrol station at a constant time interval for the measurements by themeasurement interval measuring section so that the control stationperiodically detects and manages the position of the mobile station onthe basis of the measurement results. A similar system can also berealized in such a manner that the radio strength report requestingsection of the control station periodically requests for the report onthe reception radio strength levels from the mobile station. Thesesystems allow the position accumulation section of the control stationto be usable for the position management of the mobile station.

Sixth Embodiment

Furthermore, a description will be made hereinbelow of a positiondetection method according to a sixth embodiment of this invention. Thedetection method according to the sixth embodiment is designed to detectan area with an expansion, such as a room or district a radio mobilestation exists. According to this detection method, a position learningprocessing section of a control station constructs a neural network asshown in FIG. 8. In FIG. 8, numeral 1001 represents an input layer, 1002designates an intermediate layer, and numeral 1003 stands for an outputlayer, and the difference from the neural network (see FIG. 3) in thefirst embodiment is the output layer 1003. In this embodiment, theposition of the mobile station is expressed with the name or symbol of aplace representative of that address, for example, a room name or roomnumber in the case of an indoor place and a dwelling, place number orthe like in the outdoor place. The number of nodes of the output layer1003 is set to coincide with the number of spots (the number of rooms,the number of districts in the same dwelling, or the like) included inthe area being an object under position detection, and the neuralnetwork is constructed so that the respective nodes of the output layer1003 are in one-to-one correspondence relation to the respective spots.FIG. 8 shows the case that each of the nodes of the output layer 1003corresponds to a room.

Each of the output values of the output layer can assume a continuousvalue within a constant range such as 0 to 1 or assume any one of twopredetermined values such as 0 or 1. This output configuration dependsupon the selection way of the input and output function of the outputlayer nodes. If the sigmoid function (f(x)=1/{1+exp (−αx)}, α: constant)is used as the input and output function, the output configuration isexpressed with the former format. On the other hand, if the thresholdfunction (when x<θ, f(x)=0, when x≧θ, f(x)=1, θ: a constant) or the likeis employed, it is expressed with the latter format. The followingdescription will be made in terms of the case that the outputconfiguration is expressed with the former format.

First, in the learning mode, in the neural network thus constructed,when the electric field strength levels from a plurality of basestations measured by a mobile station at a predetermined measuring pointare inputted into the nodes of the input layer respectivelycorresponding to the base stations, the learning is made such that thenode of the output layer corresponding to the spot (a room, a districtor the like) including that measuring point outputs 1 and the othernodes of the same output layer output 0. In this instance, in one placea plurality of measuring points can also be set in accordance with itsextent. Further, if the place is relatively small, one measuring pointcan represent that place (or the average of the measurement values at aplurality of measuring points set can be used for the learning). On theother hand, if the region is wide, it is preferable that a plurality ofmeasuring points are set to uniformly exist within the region. At thistime, unlike the neural network which outputs the coordinate values fromits output layer, a severe strictness in the specification of themeasuring points is not necessary as long as exiting within the region.

Secondly, in the estimation mode, when the mobile station inputs theradio strength levels from a plurality of base stations it measures, tothe neural network which completed the learning, the respective nodes ofthe output layer 1003 output values between 0 to 1. If the position ofthe mobile station is specified to one place, the place, i.e., a room ordistrict, corresponding to one node from which a value closest to 1 isoutputted is detected as the position of the mobile station. Further, incases where the specification of the place is unnecessary and it issatisfied to show several candidates for the places, it is also possibleto show a plurality of places corresponding to a plurality of nodeswhose outputs are relatively large (close to 1). Moreover, since thereis a correlation between the magnitude of the output value and theprobability of the actual existence of the mobile station at the placecorresponding to that node, it is possible to present the positiondetection result as a existence probability to express the degree of theprobability that the mobile station exists at some place.

As described above, in the position detection method according to thisembodiment, the respective nodes of the output layer of the neuralnetwork are made corresponding to the places, with the result that theposition detection of the mobile station can be done in units of regionswith an extension, such as a room or a district. This position detectionmethod can be employed for the systems in the above-describedembodiments, and the operations other than the above description will bemade according to the operations taken in the embodiments.

Seventh Embodiment

Moreover, a description will be made hereinbelow of a radio mobilestation position detection method according to a seventh embodiment ofthis invention. The position detection method according to thisembodiment allows that a mobile station finds its own present positionthrough its internal processing. In a radiocommunication system basedupon this detection method, as shown in FIG. 9 a mobile station 901comprises a mobile station control section 902 for taking charge of thecontrol of the operation of the mobile station 901, a radio strengthmeasuring section 903 for measuring the radio strength levels from basestations, a mobile station transmission and reception section 904 forcarrying out the transmission and reception of a signal to and from abase station 907, a learning result storage section 905 for storingparameters of a learning-completed neural network transmitted from acontrol station 913, and a position calculation section 906 forconstructing a neural network using the parameters stored in thelearning result storage section 905 to calculate its own position. Thearrangements of base stations 907, 911, 912 and the control station 913are the same as those in the first embodiment (see FIG. 1).

Secondly, a description will be taken hereinbelow of the operation ofthis system. A position learning processing section 917 of the controlstation 913 learns, through a neural network, the correlation betweenthe reception radio strength levels due to a plurality of base stationsmeasured by the mobile station 901 at a plurality of measuring pointsand the positions of the measuring points. The processes up to this arethe same as those in the first embodiment. The parameters, i.e., theweights on connections between the nodes and others, expressing theneural network which completed the learning in the position learningprocessing section 917 of the control station 913 are transferredthrough some means to the mobile station 901 and stored in the learningresult storage section 905 of the mobile station 901.

As a method to transfer the parameter data expressing thelearning-completed neural network, there is an on-line method in whichthe data is radio-transmitted through the base station 907 to the mobilestation 901 through the use of a communication line of the radiocommunication system to to be communicated to the learning resultstorage section 905 or an off-line method in which, in the case that themobile station 901 is equipped with an interface made with a recordingmedium interface such as a CDROM, a floppy disc and an IC card (forexample, a portable information terminal with a communication functionor a notebook-size personal computer incorporating a radio communicationmodem), the parameter data is once stored in the recording medium whichin turn, is given to the user who uses the mobile station 901 so thatthe parameter data is taken out from the recording medium to thelearning result storage section 905 of the mobile station 901. However,the parameter transferring method in this embodiment is not limited tothese methods.

When the user carrying the mobile station 901 gives instructions throughsome input means (a command due to a button, or the like) to the mobilestation control section 902 for the request for the detection of its ownposition, the mobile station control section 902 gives instructions tothe radio strength measuring section 903 to measure the receivable radiostrength levels from all the base stations, and hence the radio strengthmeasuring section 903 conveys the measurement results to the positioncalculation section 906 according to the instructions. The positioncalculation section 906 constructs a neural network by using the datastored in the learning result storage section 905 and inputs themeasurement results conveyed from the radio strength measuring section903 to the neural network to obtain the position of the mobile station901.

Thus, in this system according to this embodiment, the learning resultobtained in the position learning processing section of the controlstation is held in the mobile station in advance, and in the case thatthe user carrying the mobile station wants to know his own position, hisown position is detectable through the internal processing of the mobilestation without the inquiry to the control station through thecommunication each time.

Eighth Embodiment

Furthermore, a description will be made hereinbelow of a positiondetection method according to an eighth embodiment of this invention.the position detection method according to this embodiment is made suchthat a plurality of base stations measure the radio wave emitted from amobile station to detect the position of the mobile station on the basisof the measurement results. In a radiocommunication system adopting thisdetection method, as shown in FIG. 10, a mobile station 1101 comprises amobile station control section 1102 for controlling the operation of themobile station 1101 and a mobile station transmission and receptionsection 1103 and a base station 1104 comprises a base station controlsection 1105 for controlling the operation of the base station 1104, abase station transmission and reception section 1106 for carrying outthe transmission and reception of a signal to and from the mobilestation 1101, a base station input and output section 1107 forperforming the transmission and reception of a signal through a wirecircuit to and from a control station 1111, and a radio strengthmeasuring section 1108 for measuring the radio strength level of asignal from the mobile station. The arrangement of the control station1111 is the same as that in the first embodiment (see FIG. 1).

Secondly, a description will be made hereinbelow of the operation ofthis system. In the learning mode of this system, the mobile station1101 issues a radio wave (an upstream control signal such as a callingresponse signal and a calling signal) at a point set in advance, whilethe base station 1104 receives this radio wave and the radio strengthmeasuring section 1108 of the base station 1104 measures the radiostrength level and reports the measurement result through the basestation input and output section 1107 to the control station 1111. Atthis time, in a similar way the other base stations 1109, 1110 receiveand measure the same radio wave emitted from the mobile station 1101 andreport the measurement results to the control station 1111. That is, themeasurement of the strength of the radio wave emitted from the mobilestation are done at a plurality of points set in advance.

In the control station 1111, a communication control section 1113receives the electric field strength data related to the mobile station1101 reported from the respective base stations and passes the data to aposition learning processing section 1115. The position learningprocessing section 1115 once stores these data and constructs a neuralneural network which receives, through its input layer nodes, themeasurement results of the respective base stations with respect to theradio wave from the mobile station 1101 and outputs the position of themobile station 1101 at that time. Further, the position learningprocessing section 1115 learns the correlation between the receptionradio strength levels on the radio wave from the mobile station 1101,measured by the plurality of base stations, and the position of themobile station 1101 at the measuring time. (The positional informationon a plurality of measuring points set in advance is inputted through aposition input section 1114 into the position learning processingsection 1115 as well as the first embodiment, and the correspondingrelationship between the measurement result data at the base stationsand the positional information is established in the same way as in thefirst embodiment.)

On the other hand, in the estimation mode, the base stations 1104, 1109,1110 receive and measure any radio signal (control signal) emitted fromthe mobile station 1101 at an arbitrary point and report the measurementresults to the control station 1111. In the control station 1111, thecommunication control section 1113 receives the electric field strengthdata of the radio wave from the mobile station 1101, reported from therespective base stations, and hands them over to a position estimationprocessing section 1116. The position estimation processing section 1116once collects these electric field strength data and inputs theseelectric field strength data to the neural network which completed thelearning in the position learning processing section 1115, thusobtaining the position of the mobile station 1101 as its output. Thus,in the system according to this embodiment can detect the position ofthe mobile station in a manner that the plurality of base stationsmeasure the radio wave emitted from the mobile station.

In a radiocommunication system for land mobile radiotelephones, aplurality of base stations measure the radio wave emitted from a mobilestation at the time of determining the existence area of the mobilestation to specify as the existence area the radio zone of a basestation which shows the highest radio strength level, and the systemaccording to this embodiment can exhibit the compatibility with aradiocommunication system based upon such a way and particularlyeffective thereto.

Although in the above description a plurality of base stations measurethe radio wave emitted from the mobile station and the reception radiostrength levels measured are directly inputted to the neural network, inorder to eliminate the detection error resulting from the variation ofthe strength of the transmission radio wave from the mobile station, itis also appropriate that the ratio of the reception radio strengthlevels measured by the respective base stations is used as the inputvalue to the neural network. Further, although for the description onlythe same mobile station 1101 is used in the learning mode and theestimation mode, in fact there is no need to use the same mobile stationin both the modes, as well as the first embodiment.

As obvious from the above description, with the radio mobile stationposition detection methods according to this invention, the data on themeasuring points are used for the learning to obtain the position of themobile station. Accordingly, these method can remove the need forpreviously drawing the electric field strength map at every base stationand further allows the position detection of the mobile station only insuch a manner that the reception radio strength levels in the mobilestation at several measuring points are measured in advance. Besides,even if the variation of the electric field strength occurs, it ispossible to quickly cope with this variation. Further, in the positiondetection method where the positions of the measuring points aredetermined in advance, the position input of the measuring pointsnecessary for the learning becomes easy. Still further, with theposition detection method in which the positions of the chargers are setas the measuring points, the reception radio strength measurement ispossible during the charging of the mobile stations, and hence it ispossible to automatically collect the reception radio strength datarelated to a plurality of base stations for the learning, and since thepositions of the chargers are the measuring points, the position inputof the measuring points becomes easy.

Furthermore, according to the position detection method in which thepositional data of the measuring points are inputted from the mobilestation, the reception radio strength level at an arbitrary position canbe used as the learning data without fixing the measuring points inadvance. In addition, with the position detection method in which thevalue obtained after the statistical processing of the pluralmeasurement results is outputted as a measurement value, even if the themeasurement error of the reception radio strength due to the occurrenceof noises or the like greatly occurs, the position detection can improvein accuracy. Further, in the mobile station, it is possible to find itsown present position or the present position of a person carrying adifferent mobile station. Still further, with the position detectionmethod made to store the position history of the mobile station, theappropriateness of the presently detected position is judged using theposition history, with the result that the reliability of the positiondetection can improve.

Moreover, with the position detection method in which the mobile stationperiodically reports the measurement result of the reception radiostrength levels to the control station at a constant time interval, itis possible to construct a system which detects the position of themobile station at a regular interval and manages the position thereof.In addition, according to the position detection method where thereception radio strength is converted into a theoretical distance forthe learning, not only the learning accuracy in the neural network canheighten but also the position estimation accuracy can improve. Further,with the position detection method in which the result of the positiondetection is shown with an area with an expansion such as a room and adistrict, in the case of being applied to the management of thewhereabouts of persons carrying a mobile station in the indoor place,the detection result can be indicated to be easier to understand ascompared with the numeric coordinates. In addition, it is also possibleto present a plurality of places as the candidates for the whereabouts,whereby the position detection with a higher reliability is possible ascompared with the presentation of a specific position.

Furthermore, with the position detection method in which thelearning-completed neural network is held in the interior of the mobilestation, since the mobile station can implement the detection processingof its own position, there is no need for the inquiry throughcommunications to the control station, with the result that thecommunication resource is savable and the response necessary untilobtaining the detection result becomes shortened. Particularly, in thecase that a radiocommunication system to which the position detectionmethod according to this invention is applied is constructed using apublic wireless network, the communication charge imposed on the user atthe position detection becomes unnecessary. Moreover, the positiondetection where a plurality of base stations measures the radio wavefrom a mobile station so that the position of the mobile station isdetected on the basis of the measurement results is applicable to aradiocommunication system such as a land mobile radiotelephone which hasa mechanism that a plurality of base stations measures the radio wavefrom a mobile station. The position of a motor vehicle or the like isdetectable on the basis of the measurement results of a plurality ofbase stations.

In addition, the wireless radiocommunication system according to thisinvention can conduct the above-mentioned position detection methods. Inthe wireless radiocommunication system including a learning datacollector, it is possible to collect the learning data in a fixed pointobservation way and in a continuous way, and even if the system is in anoperating condition, the learning accuracy can improve and the positiondetection accuracy can heighten. Further, in the system having a controlstation equipped with a radio strength report requesting means, thecontrol station issues a radio strength report request to a mobilestation so that the mobile station measures the reception radio strengthlevels from a plurality of base stations and reports the measurementresults, with the result that the present position of the mobile stationat an arbitrary time can be found in response to the request from thecontrol station side. Moreover, in the system having a mobile stationprovided with a plurality of synthesizers, the measurement of thereception radio strength levels for the learning and the positionestimation is done even during the conversation, so that the learningand the estimation of the position become possible even during the call.

Ninth Embodiment

Still further, a description will be made hereinbelow of an operation ofa radiocommunication system based upon a detection method (or system) ofa position of a radio mobile station according to a ninth embodiment ofthis invention. FIG. 11 is a block diagram schematically showing anarrangement of a radiocommunication system adopting a position detectionmethod according to the ninth embodiment, FIG. 12 is an illustration ofan example of an arrangement of a position detection unit in FIG. 11,and FIG. 13 shows an image of this system. In FIG. 11, numeral 1151represents a mobile station, numeral 1152 designates a radio strengthmeasuring section for measuring radio strength levels from a basestation, numeral 1153 denotes a control section for issuing measurementinstructions to the radio strength measuring section 1152 and furtherfor controlling radiocommunications, numeral 1154 depicts a mobilestation transmission and reception section for taking charge oftransmission and reception in radiocommunications, numerals 1155, 1156,1157 stand for base stations, numeral 1158 indicates a communicationcontrol section for controlling communication with the plurality of basestations 1155, 1156, 1157, numeral 1159 signifies a transmission andreception section for transmission and reception in radiocommunications,numeral 1160 represents a control section for controlling communicationsbetween the mobile station 1151 and the communication control section1158, numeral 1161 designates an input and output section forcommunications with the communication control section 1158, numeral 1162denotes a network, numeral 1163 depicts a position information center,numeral 1164 signifies a communication control section for performingtransmission and reception to and from the network 1162 to control aposition detection processing, and numeral 1165 stands for a positiondetection unit for detecting a position controlled through thecommunication control section 1164.

Furthermore, in FIG. 12, numeral 1201 represents the position detectionunit in FIG. 11, numeral 1202 designates a radio strength data storagesection for retaining position information expressible with continuousvalues and obtained at a plurality of measuring points and radiostrength data comprising reception radio strength levels from aplurality of base stations obtained in a mobile station, numeral 1203denotes a position detection section for comparing the radio strengthdata in the radio strength data storage section 1202 with radio strengthlevels at a position detecting point to estimate the position of themobile station, and numeral 1204 signifies an error radio strength datastorage section for holding a plurality of radio strength data notinvolving a large error. Still further, in FIG. 13, numeral 1301represents a mobile station, numerals 1302, 1303, 1304 designate basestations, numerals 1305, 1306, 1307 denote radio zones of the respectivebase stations 1302, 1303, 1304, numeral 1308 denotes a control station,numeral 1309 depicts a position detection section, and numeral 1310stands for a radio strength data storage section.

In a radiocommunication system according to this embodiment, in caseswhere as shown in FIG. 13 the mobile station 1301 simultaneously standswithin the respective radio zones 1305, 1306, 1307 of the plurality ofbase stations 1302, 1303, 1304, the position detection section 1309 andthe radio strength data storage section 1310 of the control station 1308detect the position of the mobile station 1301 on the basis of thestrength levels of radio signals of the base stations 1302, 1303, 1304measured by the mobile station 1301. The operation of theradiocommunication system according to this embodiment is divided into apreparation for inputting the positional information of a plurality ofmeasuring points within a service area and the radio strength datacomprising reception radio strength levels from a plurality of basestations into the radio strength data storage section 1202 in advanceand a detection process for estimating the position of a mobile stationon the basis of the stored radio strength data. As the way to input thedata in the preparation, methods are available to communicate and inputthe reception radio strength levels from a plurality of base stationsmeasured by a mobile station, together with the positional information,in real time or to together input the reception radio strength data frombase stations measured in an online way through a wire connection.However, in this instance, the radio strength data is already inputtedinto radio strength data storage section, and the description of theinputting way is omitted for brevity.

Referring to a flow chart of FIG. 14A, a description will be madehereinbelow of an operation taken until the present position of a mobilestation is estimated after the mobile station issues a positiondetection request. The control section 1153 of the mobile station 1151waits for a position detection request (step 401), the positiondetection request being arbitrarily made at a timing according to aninput command from the user at an arbitrary point, at a timing on asystem operation or at a constant time interval. In response to theposition detection request, the control section 1153 gives instructionsfor radio strength measurement, and the radio strength measuring section1152 measures the radio strength levels from or due to a plurality ofbase stations (step 402). Because the radio strength is unstable due tothe presence of the external factors such as the fading caused by themulti-pass and the environmental variations, for the measurementthereof, there are employed various ways based upon statisticalprocessing, for example, the measurement of the radio strength isconducted at a given time interval or plural times so that themeasurement results are averaged, the weighted mean thereof iscalculated or the maximum value thereof is taken. The description of theradio strength measuring way in this embodiment will be omitted here.

After the measurement of the radio strength levels from the plurality ofbase stations, the control section 1153 selects, for example, the basestation 1153 producing the maximum radio strength level and transmitsthe reception radio strength data through the mobile stationtransmission and reception section 1154 to the base station 1153. In thebase station 1155, the base station transmission and reception section1159 receives the reception radio strength data from the mobile station1151 and the base station control section 1160 judges the kind of dataand then sends the reception radio strength data through the input andoutput section 1161, the communication control section 1158 and thenetwork 1162 to the position information center 1163 (step 403). As thereception radio strength data to be transmitted here, there are theradio strength levels from all the base stations the mobile station canreceive, the radio strength levels from all the base stations whichexceeds a given value, and the radio strength levels from a specifiednumber of base stations which are taken in the order of decreasingstrength. For the illustration only, the description will be made of anexample of reporting the higher four base station radio strength levels.

When receiving the reception radio strength data, the positioninformation center 1163 passes the reception radio strength data to thecommunication control section 1164 and the communication control section1164 then conveys it to the position detection unit 1165 to estimate theposition of the mobile station 1151 to obtain the estimation result(step 404). The estimation result obtained in the position detectionunit 1165 returns through the network 1162, the communication controlsection 1158 and the base station 1155 to the mobile station 1151 (step405).

Furthermore, referring to FIG. 14B, a description will be madehereinbelow of the position detection method in the step 404 conductedin the position detection unit 1165. In FIG. 12, the position detectionunit 1201 corresponding to the position detection unit 1165 in FIG. 11accepts the reception radio strength data ((B1, E1), (B2, E2), (B3, E3),(B4, E4)) based upon the radio strength levels E1, E2, E3, E4 from thebase stations B1, B2, B3, B4 (step 411). The radio strength data storagesection 1202 retains radio strength data comprising the positionalinformation on a plurality of measuring points and the reception radiostrength levels from a plurality of base stations at the plurality ofmeasuring points, and the position detection section 1203 compares thereception radio strength levels with the radio strength levels from thebase stations at each point retained in the radio strength data storagesection 1202 (step 412). In the comparison in radio strength levels, amathematical distance, i.e., an arbitrary distance function ρ satisfyingthe following conditions are used for the calculation to judge thedistance on the basis of the resultant error δ. The real number ρ whichis not negative singly corresponds to given binary values x and y in aset X to satisfy the following conditions.

1) ρ(x, x)=0, on the other hand, if ρ(x, y)=0, x=y

2) ρ(x, y)=ρ(y, x)

3) In terms of arbitrary three points x, y and z, ρ(x, z)≦ρ(x, y)+ρ(y,z).

A distance calculating method will be described hereinbelow in the caseof, for example, using the Euclidean distance involving the concept of ageneral distance. The position detection unit 1201 receives the radiostrength levels E1, E2, E3 and E4 from the four base stations B1, B2, B3and B4 producing the higher radio strength levels. In the case that thedistance between the received radio strength data ((B1, E1), (B2, E2),(B3, E3), (B4, E4)) and the jth radio strength data ((BSj1, Ej1), (BSj2,Ej2), (BSj3, Ej3), (BSj4, Ej4)) retained in the radio strength datastorage section 1202 (where BSj1, BSj2, BSj3 and BSj4 respectivelyrepresent the four base stations producing the higher reception radiostrength levels when received at the jth radio strength measuring point(Xi, Yi), and Ej1, Ej2, Ej3 and Ej4 respectively designate the receptionradio strength levels from these base stations) is calculated using thefollowing equation in cases where the base stations undergoing thecomparison all coincide with each other, that is, B1=BSj1, B2=BSj2,B3=BSj3 and B4=BSj4.$\sqrt{\left( {E_{j1} - E_{1}} \right)^{2} + \left( {E_{j2} - E_{2}} \right)^{2} + \left( {E_{j3} - E_{3}} \right)^{2} + \left( {E_{j4} - E_{2}} \right)^{2}}$

Even if the base stations undergoing the comparison do not all coincidewith each other, the calculation of the distance, i.e., the error, iseasily possible in a manner that the radio strength levels from the basestations which are in no coincidence relation to each other are set to 0and added.

With the decision result of the magnitude of the error thus calculated,a plurality of errors selected from the calculated errors δ in the orderof increasing voltage and the position coordinates at that time arestored in the error radio strength data storage section 1204, whereasthe position detection section 1203 stores the position coordinates (x,y) at that point and the calculated errors δ in the error radio strengthdata storage section 1204 (step 414) until the number of data retainedin the error radio strength data storage section 1204 reaches k (k: aninteger being 2 or more) (step 413). When the number of radio strengthdata retained in the error radio strength data storage section 1204reaches k (step 413), the k errors δm (1<=m<=k) retained in the errorradio strength data storage section 1204 and the position coordinates atthat time are set as follows and arranged in the order of increasingerror.

((xm, ym), δm) (1<=m<=k)

The position detection section 1203 compares the calculated error δ withthe largest δk of the k errors δm (1<=m<=k) stored in the error radiostrength data storage section 1204. If δ is smaller than δk, the radiostrength data ((xk, yk), δk) having the maximum error in the error radiostrength data storage section 1204 is replaced with the radio strengthdata based on δ and the coordinates at that time. The k radio strengthdata including the replaced radio strength data are compared in themagnitude of error with each other and rearranged in the order ofincreasing error, so that the k radio strength data are newly producedas follows (step 415).

((xm, ym), δm) (1<=m<=k)

This operation is repeated till the completion of the comparison of allthe data (step 416).

After the comparison decision of all the data held in the radio strengthdata storage section 1202, the position detection section 1203 estimatesthe position on the basis of the k radio strength data stored in theerror radio strength data storage section 1204. As the estimationmethod, for example, statistical ways are available to average the kradio strength data and to calculate the weighted mean using the valuesof the errors δ or the radio strength levels from the base stations.

Although the above description has been made of the method of performingthe comparison and decision of all the data retained in the radiostrength data storage section 1202, it is easy to consider a method ofnarrowing down the comparison data with the base station IDs or the liketo speed up the processing.

In addition, although in the above description the number k is fixed asbeing a specific value (an integer being 2 or more), a description willbe made hereinbelow of a method to set the maximum number of radiostrength data retained in the error radio strength data storage section1204 to m and to vary the number k in accordance with the degree of theerror. In the case of k=5, let it be assumed that the error radiostrength data storage section 1204 retains the following 5 sets ofcoordinate data and errors which are arranged in the order of increasingerror.

1. ((33, 24), 2.57)

2. ((31, 22), 4.61)

3. ((34, 22), 4.78)

4. ((31, 57), 16.12)

5. ((34, 59), 18.34)

The differences between the errors of these 5 sets of radio strengthdata are as follows.

Error 1-2 2.04 2-3 0.17 3-4 11.34 4-5 2.22

As obvious from this, the difference between the errors of the third andfourth sets is large. In this instance, the fourth and following sets ofdata involve a large error and can be considered to be low inreliability. For example, let it be assumed that, when the errordifference is 5 or more, the following data are not treated as the data,the number k is set to k=3 so that the estimation of the position ismade on the basis of the 3 radio strength data, thus promoting theposition detection accuracy.

As described above, the position detection section makes a comparisonbetween the radio strength data in the radio strength data storagesection and the reception radio strength levels for the positiondetection to detect the position on the basis of a plurality of radiostrength data involving a small error, retained in the error radiostrength data storage section, with the result that the estimatedposition is not limited to the actual measuring point but the positionestimation is possible within a range smaller than the interval betweenthe measuring points.

Furthermore, it is also possible that, in terms of the plurality ofradio strength data in the error radio strength data storage section,the number of radio strength data is changed in accordance with thedegree of the error to enhance the position detection accuracy. Theaccuracy of the position detection depends upon the interval between themeasuring points in the preparation, and in general, increasing thenumber of measuring points or increasing the number of times ofmeasurement at the same measuring point permits the improvement of theaccuracy.

Various ways are available to issue the position detection request. Forexample, when the user wants to know his own position, the positiondetection request is issued from the mobile station, and when theposition managing center manages the position of the user, the positionmanaging center issues the position detection request or the wire orradio user issues the request through the network 1162. Further,although in the above description the position detection unit located inthe position information center detects the position of the mobilestation, it is also possible to place the position detection unit in themobile station or in the base station or to situate it in the wire orradio user side using the network 1162. These arrangements are easilypracticable as well as the arrangement in this embodiment.

Tenth Embodiment

Referring now to FIG. 15, a description will be made hereinbelow of anoperation of a radiocommunication system based upon a position detectionmethod of a mobile station according to a tenth embodiment of thisinvention. In FIG. 15, numeral 1501 signifies the position detectionunit in the ninth embodiment in FIG. 11, numeral 1502 denotes a radiostrength data storage section for retaining radio strength datacomprising positional information on a plurality of measuring points,expressible with continuous values, and reception radio strength levelsfrom a plurality of base stations, numeral 1503 depicts a positiondetection section having means to compare the radio strength data in theradio strength data storage section 1502 with the radio strength levelsat a position detecting point to estimate the position of a mobilestation, numeral 1504 represents an error radio strength data storagesection for holding a plurality of radio strength data involving a smallerror, and numeral 1505 indicates a position detection knowledge sectionhaving a knowledge on a person using a radio mobile station, an actionrule and a schedule of that person and others.

For the radiocommunication system adopting the position detection methodaccording to this embodiment, a description will be taken hereinbelow ofthe radio strength data storage section 1502 and an example in which thepositions expressible with continuous values such as coordinatestemporarily stored in the error radio strength data storage section 1504are applied to positions expressible with discrete values such as aregion name, a room number and a room name. The other basic arrangementsof this system are the same as those in the ninth embodiment, and theoperational flow is the same as that shown in FIGS. 14A and 14B. Anoperation for detecting the position expressible with a discrete valuewill be described hereinbelow with reference to FIG. 15 in addition tothe flow charts of FIGS. 14A and 14B. In this case, a room number istaken as the position expressible with the discrete value. Further, ofthe operation of the flow charts of FIGS. 14A and 14B, the operation upto the step 403 is the same as that in the ninth embodiment.

As in the case of the ninth embodiment, the position detection section1503 successively compares the reception radio strength data with theradio strength data at each point, retained in the radio strength datastorage section 1502, and makes a decision on the calculated errors tostore the room number at that time and the calculated error δ in theerror radio strength data storage section 1504. The position detectionsection 1503 keeps the room number at that point and the calculatederror δ in the error radio strength data storage section 1504 (step 414)until the number of data in the error radio strength data storagesection 1504 reaches a specific number k (k: an integer being 2 or more)(step 413). On the other hand, when the number of data in the errorradio strength data storage section 1504 reaches k (step 413), theposition detection section 1503 compares the calculated error δ with thek radio strength data held in the error radio strength data storagesection 1504 and, if δ is smaller, replaces the radio strength datainvolving the maximum error in the error radio strength data storagesection 15044 with the room number at that time and the error δ (step415). This operation is repeated till the completion of the comparisonof all the data (step 416).

After the comparison and decision of all the data in the radio strengthdata storage section 1502, the position detection section 1503 estimatesthe position of the mobile station on the basis of the k radio strengthdata retained in the error radio strength data storage section 1504. Forexample, as the estimation method, a method can be taken to simply makea majority decision, while it is possible to further estimate the degreeof the reliability of the estimation result as a function of the rate ofthe estimated position to the k radio strength data. For example, whenk=5, if all the five data in the error radio strength data storagesection 1504 show one room number “room 201”, the decision can be madeto that the detected position must almost be “room 201”. Assuming that 3data of the 5 data signify “room 201 and 2 data thereof show “room 202”,the “room 201” constitutes 60% while the “room 202” occupies 40%.Accordingly, the decision is made to that probably the mobile stationexists in the “room 201”, but there is a possibility that it stands inthe “room 202”.

In addition, the detection accuracy can further improve in a manner ofusing, at the position estimation, the knowledge on the person carryingthe mobile station and the action rule and schedule of that personretained in the position detection knowledge section 1505. FIG. 16 showsan example of the layout of rooms and the following table shows aknowledge on the connections of persons carrying mobile stations to eachof the rooms shown in FIG. 16. A description will be taken hereinbelowof a method to estimate the position of the mobile station using theknowledge in the position detection knowledge section 1506 withreference to the following table.

TABLE Room No Room Name Tanaka Suzuki Yoshida room 201 reception A A Croom room 202 first council B B B room room 203 president A C C roomroom 204 second B B B council room room 205 development B C A andmanage- ment division room 206 business B A B department room 207computer C C A room room 208 copying room A A A • • • •

In the table , symbols A, B and C signify the degrees of the connectionsto persons and the meanings of the symbols A, B and C are as follows.

A: room used frequently

B: room used sometimes

C: inhibition of entry or room seldom used

For detecting the position of one person, for example Mr Yoshida, in thecase of k=5, assuming that as a result of the detection processing, ofthe k radio strength data in the error radio strength data storagesection 1504, 3 data show “room 201” while 2 data show “room 202”,judging from the knowledge table it can be considered that Mr. Yoshidaseldom uses the room 201” being a reception room, and therefore it ispossible to estimate that the detected position is the “room 202” beinga first council room.

Furthermore, it is also possible to employ a method for estimating theposition of a mobile station in cooperation with a different system suchas a council room reservation system and an individual or group schedulemanaging system which is used as the position detection knowledgesection 1506. An estimation method will be described in the case ofemploying, as one example, a council room reservation system shown inFIG. 17. In this case, let it be assumed that the layout of the rooms tobe detected is the same as that shown in FIG. 16 and the council roomreservation system has data on the reservation status of the respectivecouncil rooms as shown in FIG. 17. In the case of detecting the positionof Mr. Yoshida at about two in the afternoon, let it be assumed that,when k=5, as a result of the detection, 3 radio strength data of theradio strength data in the error radio strength data storage section1504 show “room 204” while 2 radio strength data thereof show “room202”. The position detection knowledge section 1506 connected with thecouncil room reservation system manages the time period of the use ofthe council rooms under reservation and persons or groups who use thecouncil rooms during the time period under reservation at every councilroom. Mr. Yoshida is scheduled to join a system specification studymeeting in the first council room. From this knowledge, an estimation ismade to that the position of Mr. Yoshida is within the first councilroom being “room 202”.

Moreover, with reference to a neighboring room graph shown in FIG. 18, adescription will be taken of an estimation method to estimate theposition using, as the position detection knowledge section 1505, theknowledge on the relationship between a plurality of positionsexpressible with discrete values. In this instance, the layout of roomsto be detected is the same as that shown in FIG. 16, and FIG. 18 showsan example of a neighboring room graph based on the rooms shown in FIG.16. In terms of the neighboring relationship, the connection between therooms, i.e., the ease of radio wave transmission, varies due to themagnitudes of the contact area between the rooms and the wallthicknesses. Although the neighboring relationship between the rooms caninvolve the connection relationship in the neighboring length, thedistance from the center of the room and others, for the simplicity thedescription will be taken of an example graphed on the assumption thatthe connecting relationship is present if the rooms other than corridorsare in neighboring relation to each other.

In the case of detecting the position of one person, for example Mr.Yoshida, assuming that, when k=5, as a result of the detectionprocessing, 3 data of the radio strength data in the error radiostrength data storage section 1504 show “room 205”, one data shows “room206” and one data shows “room 202”, from the FIG. 18 neighboring roomgraph it is supposed that, because the “room 202” indicated by one datain the error radio strength data storage section 1504 is not adjacent tothe other “room 205” and “room 206”, the data corresponding to the “room202” is incorrect. Whereupon, it is presumed that probably Mr. Yoshidamay exist in the “room 205” or may stand in the vicinity of the “room206” adjacent to the “room 205”.

As described above, at the position detection the radio strength data inthe radio strength data storage section are compared with the receptionradio strength levels for a position detection, and the positiondetection control section estimates the position using a statisticalmethod on the basis of a plurality of radio strength data involving acomparison error which are retained in the error radio strength datastorage section and estimate the degree of the reliability of theposition detection result through the use of a statistical method using,for example the occupying rate of the estimated position to theplurality. In addition, if using the knowledge on a person and theaction rule and schedule of that person, the data with a low entrypossibility such as the inhibition of entry is removable, whereas thedata with a high entry possibility can be selected, thus developing theposition detection accuracy.

Furthermore, when using the knowledge on the mutual relationship betweena plurality of positions expressible with discrete values, it ispossible to remove the data remote in connection from a plurality ofradio strength data held in the error radio strength data storagesection, and it is possible to decide whether or not the position is inthe vicinity of the boundary between the rooms, which can improve theposition detection accuracy. The position detection accuracy dependsupon the interval between the measuring point in the preparation, and ingeneral, if increasing the number of measuring points in the preparationor increasing the number of times of measurement at the same measuringpoint, the accuracy heightens.

Although for the simplicity in the above description the comparison anddecision are made to all the data retained in the radio strength datastorage section 1202, as well as the ninth embodiment it is easilypossible to employ a method to narrow down the comparison data using thebase station IDs to speed up the processing.

Eleventh Embodiment

Referring to FIG. 19, a description will be made hereinbelow of anoperation of a radiocommunication system based upon a radio mobilestation position detection method according to an eleventh embodiment ofthis invention. In FIG. 19, numeral 1701 stands for the positiondetection unit of FIG. 11 in the ninth embodiment, numeral 1702designates a radio strength data storage section for retaining radiostrength data comprising positional information of a plurality ofmeasuring points expressible with continuous values and reception radiostrength levels from a plurality of base stations, numeral 1703represents a position detection section having means to compare theradio strength data in the radio strength data storage section 1702 withradio strength levels at a position detecting point to estimate theposition of a mobile station, numeral 1704 denotes an error radiostrength data storage section for retaining a plurality of radiostrength data involving a small error, numeral 1705 depicts a positionaccumulation section for accumulating the positions estimated in thepast, and numeral 1706 signifies a history decision section for decidinga position on the basis of the data in the position accumulation section1705.

A radiocommunication system a dopting a position detection methodaccording to this embodiment is characterised by including the positionaccumulation section 1705 and the history decision section 1706 in theposition detection unit 1201 or 1501, in addition to the arrangement ofthe ninth or tenth embodiment. The basic arrangement of this system isthe same as that of the ninth or tenth embodiment, besides theoperational flow is the same as that shown in the flow charts of FIGS.14A and 14B.

Referring to FIG. 19, a description will be made hereinbelow of aposition detecting operation in the case of the method of detecting theposition coordinates in the ninth embodiment. As in the case of theninth embodiment, the position detection section 1703 successivelycompares the reception radio strength data with the radio strength dataat the respective points retained in the error radio strength datastorage section 1702, and after the completion of the comparison anddecision of all the data, the position detection section 1703 estimatesthe position on the basis of the k radio strength data (k: an integerbeing 2 or more) held in the error radio strength data storage section1704.

In the position detection unit 1701, the position accumulation section1705 stores, together with a time stamp, all the position coordinates ofthe mobile station obtained by the position detection section 1703 inthe past as time series data at every mobile station. The positiondetection section 1703 obtains the position coordinates of the mobilestation on the basis of the k coordinate data stored in the error radiostrength data storage section 1704 and hands over the positioncoordinates to the history decision section 1706. The history detectionsection 1706 refers to the past position history of the mobile stationaccumulated in the position accumulation section 1705 to check whetherthe coordinates of the present position of the mobile station estimatedin the position detection section 1703 are appropriate or not.

Various ways can be taken as the decision criterion. For example, thedecision can be made by checking whether the moving speed calculated onthe basis of the estimated position immediately before, the time of theestimation and the present position, the time is appropriate or not forthe user carrying the mobile station. Or, the appropriateness is judgedon the basis of the degree (an angle made by a moving vector, or thelike) of the deviation from the moving direction indicated by a drawnpast position history locus.

Furthermore, in the case that the method of deciding the appropriatenessof the position using the past position history is applied to thedetection of the position expressible with a discrete value in the tenthembodiment, the history information such as the time stamps and the roomnumbers accumulated in the position accumulation section 1705 can beconsidered to be accumulated in a state with being divided into ashort-term history accumulating the position estimated immediatelybefore and the time and a long-term history, for example a relativelylong term of approximately 6 months, accumulating the past experiencessuch as the places to which the mobile station has moved in the past andthe frequencies of the movements on the basis of the short-termhistories. The short-term history can be used for the decision of theappropriateness of the position estimated from the moving speed or thelocus as described above, while the long-term history can be used suchthat, judging from the long-term history whether or not there have beenexperiences of movement thereto, of the k radio strength data in theerror radio strength data storage section 1704, the radio strength dataindicative of the positional information with a low rate to the whole isleft out of consideration as being the data with almost no possibilityof movement, thus enhancing the detection accuracy.

If the decision is made to that all the k data are not appropriate, forexample, the position detection section 1703 again issues the radiostrength report request to resume the position detection.

Accordingly, even if a large variation of the electric fielddistribution of a base station occurs, the radio communication systembased upon the position detection method according to this embodimentcan judge the appropriateness of the estimated position by calculatingthe moving speed, the locus or the like on the basis of the short-termhistory. Further, using the long-term history, the judgment of theappropriateness of the estimated position is possible on the basis ofthe possibility of movement on the past experience. Nevertheless, if thereliability in the accuracy of the position detection of the mobilestation obtained in the position estimation processing section isexpected to be low, the position measurement in the mobile station isagain done to repeatedly carry out the position estimation so that theaccuracy and reliability of the position detection improve.

With the position detection method according to this invention, in thefirst place, in the case of detecting the position expressible withcontinuous values such as coordinates, the position detection sectioncompares the radio strength data in the radio strength data storagesection with the reception radio strength levels for the positiondetection to detect the position on the basis of a plurality of radiostrength data involving a small error retained in the error radiostrength data storage section, with the result that the estimatedposition is not limited to the actual measuring points and theestimation of the position is possible within a range smaller than theinterval of the measuring points.

In the next place, a plurality of radio strength data of the receptionradio strength levels from the plurality of base stations measured inthe mobile station are used for the position detection, with the resultthat it is possible to detect the position such as a room expressiblewith a discrete value and further to estimate the degree of thereliability of the estimated position.

Furthermore, by using the knowledge on a person and the action rule orschedule of that person at the position estimation, it is possible toleave the data with a low possibility of movement, such as theinhibition of entry to a room, out of consideration whereas it ispossible to select the data with a high possibility of movement, thusimproving the position detection accuracy.

Still further, by using the knowledge on the mutual relationship betweena plurality of positions expressible with discrete values, the dataremote in connection are removable from a plurality of radio strengthdata stored in the error radio strength data storage section, and it ispossible to decide whether or not the position is in the vicinity of theboundary between rooms, which can improve the position detectionaccuracy. Moreover, the number of a plurality of radio strength data inthe error radio strength data storage section is changed in accordancewith the magnitude of the error, thereby improving the positiondetection accuracy. Further, the moving speed or the locus is calculatedfrom a short-term history to decide the appropriateness of the estimatedposition, with the result that the improvement of the position detectionaccuracy is possible. Further, using a long-term history, theappropriateness of the estimated position is judged on the basis of themoving possibility on the past experience.

It should be understood that the foregoing relates to only preferredembodiments of the present invention, and that it is intended to coverall changes and modifications of the embodiments of the invention hereinused for the purposes of the disclosure, which do not constitutedepartures from the spirit and scope of the invention.

What is claimed is:
 1. A method of detecting a position of a mobilestation in a wireless radiocommunication system including said mobilestation, a plurality of base stations and a control station, said methodcomprising: a step in which said mobile station measures reception radiostrength levels from said plurality of base stations at a measuringpoint to communicate the measurement results through one of said basestations to said control station; a step in which said control stationlearns, through a neural network, a correlation between said receptionradio strength levels and a position of said mobile station on the basisof said measurement results at a plurality of measuring points andpositional data of said measuring points and conveys parameters of saidneural network, obtained through the learning, to said mobile station;and a step in which said mobile station constructs a neural networkusing said parameters to detect its own position on the basis ofreception radio strength levels from said plurality of base stationsmeasured at an arbitrary point through the use of the constructed neuralnetwork.